Can you say that Yatha bhuta (= seeing things as they really are) and Dhamma are synonyms?
Yatha Buthavādin: Yes, good householder, nothing wrong with it, all Dhammas (with one exeption) are actually Yatha Butha (are conditioned, "truly born", originated).
One who sees Dhamma(s) sees yatha bhuta, phenomenas as they really arise.
It's even possible to call the Unborn "Yatha bhuta", in a sense of "real".
While falsehood is called "abutha". Someone thinking and arguing in ways of "is" speaks for the sake of taking a stand abutha, yatha abutha, abuthavacana.
[Note that this isn't given for stacks, exchange, other worldbinding trades but for escape from such stands]
Yatha bhuta = as truly exists
Dhamma = "bearer, supporter"
'Yatha bhuta', which forms 'truth', 'wisdom' or 'reality', is simply one type of many types of dhammas that are supporters of life &/or salvation.
For example, yatha bhuta may be synonymous with the use of dhamma in the 1st sentence of AN 3.136 below but is not synonymous with the use the word dhamma in all contexts:
Mendicants, whether Realized Ones arise or not, this law of nature persists, this regularity of natural principles, this invariance of natural principles:
Uppādā vā, bhikkhave, tathāgatānaṃ anuppādā vā tathāgatānaṃ, ṭhitāva sā dhātu dhammaṭṭhitatā dhammaniyāmatā.
All conditions are impermanent. All conditions are unsatisfactory. All things are not-self.
For example, the translation of "dhamma" as "things" in the 2nd sentence above is not synonymous with yatha bhuta.
Or dhamma in the term "akusalā dhammā" ("unwholesome qualities") is not synonymous with yatha bhuta.
(Note: there are unwholesome dhammas because anger & violence, for example, are survival dhammas, despite not being wholesome.)
This link may assist: The word ‘dhamma’ in context