SO the summary is that you must not confuse the noble 8 fold path with the humanism pushed by puthujjanas, you must not let the mind be afflicted by the body, you must not be blind to the danger of sensuality, you must judge your thoughts and sanna and vedana all day long, you must become sensitive to the sankharas in order to destroy them.
The hardest part is to be sensitive to the ''joy of renunciation'' and the samma smadhi will come by the usual formula:
''living thus heedfully, joy arises''
https://www.accesstoinsight.org/tipitaka/sn/sn55/sn55.040.than.html
It is mano which has piti and the kaya has passambhati then sukhaṃ vediyati, and the citta has sukhha then samadhi.
Like any humanist, The puthujjana Upasaka Culadasa confuses being a humanist, having compassion, with the ''kamma that is neither dark nor bright with neither dark nor bright result, leading to the ending of kamma''. That's a typical mistake created by puthujjanas who refuse the nekhamma part of samma sankappa, whereas not having nekhamma is just as detrimental as having ill-will.
http://www.buddha-vacana.org/sutta/anguttara/05/an05-090.html
Those people cling to sensuality and their typical behavior is that they feel sad when they see puthujjanas not having stuff, so they say that they are good people, because ''they have compassion'' and because they give'' stuff to destitute puthujjanas, because when the destitute puthujjanas has stuff, this puthujjana is no longer sad.
Of course, this behavior relies on craving, on kamma, on sankharas and jayati so it never ever ends the dukkha of the puthujjana who gives stuff nor the dukkha of the destitute puthujjana.
This is explained here https://legacy.suttacentral.net/en/an7.52
The good thing about the doctrine created by the puthujjana Upasaka Culadasa is that even though you get wrong concentration by following his directions, you avoid one of the most moronic & toxic idea ever created by a puthujjana : to wit, mixing the dhamma with ''the dark night'' created the christian puthujjanas who develop the ''dry insight'' doctrine in the west, [christian puthujjanas who talk about the dhamma cling to their christian vocabulary]. Those people completely fail to understand that any insight into dukkha does not generate more dukkha. THis is because those puthujjanas are eager to declare themselves as ''having insights'', as ''reaching first path'', as ''cycling through insights'' and plenty of other toxic words expressing their toxic ideas.
Instead of talking about the various wrong samadhi invented by various puthujjanas, it is way better to focus on right sammadhi, or even better on rigth liberation.
The difficulty with the right liberation is that The right liberation can be expressed by the vocabulary used for the wrong liberations.
http://obo.genaud.net/dhamma-vinaya/pts/sn/04_salv/sn04.41.007.wood.pts.htm#p1
but like the buddha says, the best[=non-ambiguous] and unique way to speak of the right liberation is
Truly that unshaken heart's release is void of lust, void of hate,
void of illusion.
For instance, there are plenty of wrong liberations and then puthujjanas wonder what is the difference between those wrong liberations and the right liberation:
"Housefather, this heart's release and this utterly unworldly[2]
heart's release, and this heart's release that is by the void and that
which is signless, - are these states diverse in spirit, diverse in
letter, or are they the same both in spirit and in letter?"
"There is one view of the question,[3] sir, according to which these
states are diverse both in spirit and in letter.
But there is another view, sir, according to which they are one and
the same both in spirit and in letter.
Let's recall that the only goal of the dhamma is to end dukkha, and it turns out that ending dukkha is about viraga, nirodha, Paṭinissaggā and ''the letting go'' that puthujjanas misuse and plenty of other words like extinction.
"Householder, through the destruction, fading away, cessation, giving
up, and relinquishment of desire, lust, delight, craving, engagement
and clinging, mental standpoints, adherences, and underlying
tendencies towards the form element, the mind is said to be well
liberated.
The buddha had plenty of wrong concentration before getting the right concentration, which are the jhanas, and then later on ''turning the citta'' to the famous 3 knowledges which are the insights into kamma, jayati and dukkha.
So like he said after remarking his failure to end dukkha, he started from scratch. For a puthujjana, starting from scratch means judging thoughts and sanna-vedana, because puthujjanas crave basing their life and actions on their thoughts and sanna-vedana. The biggest problem for puthujjanas is that they do not know what are meritorious thoughts and meritorious vedana-sanna, and the demeritorious thoughts and sanna-vedana.
SO starting from scratch means judging thoughts and sanna-vedana each hour of each day of each week of each month. That's really hard for most puthujjanas. THe citta who watches and judges thoughts and sanna-vedana has the samadhi called the sati sampajaanna http://www.buddha-vacana.org/sutta/anguttara/04/an04-041.html
Even though he claimed that nekhamma and metta are good, he still failed to get the citta into samadhi, precisely because he still lusted towards the opposite of those https://www.accesstoinsight.org/tipitaka/an/an09/an09.041.than.html
Failing to see the dangers of the aggregates is the way to never have the joy of the nekhamma, to have the mind afflicted by the aggregates, like the buddha explains to Nakulapita, in the Nakulapita Sutta
"And how is one afflicted in body but unafflicted in mind? There is
the case where a well-instructed disciple of the noble ones — who has
regard for noble ones, is well-versed & disciplined in their Dhamma;
who has regard for men of integrity, is well-versed & disciplined in
their Dhamma — does not assume form to be the self, or the self as
possessing form, or form as in the self, or the self as in form. He is
not seized with the idea that 'I am form' or 'Form is mine.' As he is
not seized with these ideas, his form changes & alters, but he does
not fall into sorrow, lamentation, pain, distress, or despair over its
change & alteration.
"He does not assume feeling to be the self...
"He does not assume perception to be the self...
"He does not assume fabrications to be the self...
"He does not assume consciousness to be the self, or the self as
possessing consciousness, or consciousness as in the self, or the self
as in consciousness. He is not seized with the idea that 'I am
consciousness' or 'Consciousness is mine.' As he is not seized with
these ideas, his consciousness changes & alters, but he does not fall
into sorrow, lamentation, pain, distress, or despair over its change &
alteration.
"This, householder, is how one is afflicted in body but unafflicted in
mind."
It turns out that the good thoughts and sanna-devana are the thoughts of nekhamma and metta and the good sanna-vedana are whatever sanna-vedana there is in samma samadhi. When the citta is in samma samadhi, ''you make merit'', like puthujjanas say, and the ''contact'' generating the sanna-vedana are meritorious. [and then when there is a jayati, , it is in the higher realms and the contact is good].
The other way to make merit outside samadhi is explained here https://www.accesstoinsight.org/tipitaka/an/an03/an03.057.than.html
Having right samadhi is good and since a puthujjana who trains to end dukkha has sati, this puthujjana has memorized that right samadhi is the way to slide towards nibanna, viraga, nirodha , Patinissagga, the ending of the sankharas, of the asavas, of whatever stems from ignorance.
https://obo.genaud.net/dhamma-vinaya/pts/sn/05_mv/sn05.53.001-012.wood.pts.htm
This is what sotapannas have to do to finish the path, because right samadhi means to see properly the dhammas [puthujjanas speculate on this by wondering whether dhammas here means ''phenomena or the teaching, but it is not important]
accesstoinsight.org/tipitaka/sn/sn22/sn22.005.than.html
The Blessed One said: "Develop concentration, monks. A concentrated
monk discerns in line with what has come into being. And what does he
discern in line with what has come into being? The origination &
disappearance of form. The origination & disappearance of feeling...
perception... fabrications. The origination & disappearance of
consciousness.
THe way for a sotapanna to reach anagamin is the first jhana
even so in the Ariyan disciple arises the flawless, taintless eye of
wisdom,[12] and along with this arising three fetters are abandoned,
to wit:
The view of the person-pack,[13] doubt-and-wavering and wrong handling
of rite and ritual.
Nay more, he departs from two things, coveting and malevolence.
This disciple, aloof from sensual desires, aloof from unprofitable
states, entering on the first musing, which is accompanied by thought
directed and sustained, born of seclusion, zestful and easeful, dwells
therein.
[222] At such time, monks, if the Ariyan disciple should make an end,
there is no fetter bound by which he would come back again to this
world.'[14]
Once you are good at getting the citta in samadhi, you can try anapanasati, because The result of anapanasati is always nibanna.
In terms of sankharas, anapanasati means the destruction of sankharas, and reaching viraga and all that. Before destroying the sankharas, you need to tranquilize them and before tranquilizing the sankharas, you need to be sensitive to the sankharas. So it always goes like this
**
be sensitive to sankharas --->calm the sankharas--> destroy the
sankharas
**