Learning -- If by this word
within infinite spiritual domain, you mean as ," a type of simple but pure(dedicated towards goal) practice to understand, feel & get established into dhamma(Right teaching)".
Then yes, One can follow any path(householder or homeless or mix like this and this) and will be able to arrive at the same goal through
Goal-- means to achieve state of enlightenment.
It's the behaviour through which it can be said that the stated person/s above or below were either stream-enterer or enlightened ones.
Assuming that you are not a blind fan of buddha to the extent that you call only Gautama the buddha to be an enlightened one, whereas there are still other respectables like this 1, this 2, this 3 etc., there might be others of whom you would have heard in your locality as well. Along with this as per buddhism, once stream-entry occurs- journey will definitely end at same goal.
Even if you are, dhamma teaches us to respect other philosophies as well.
So here is my experience till now,
What can those following the Theravada learn when studying the Mahayana as the Mahayana see it?
My Ego remains satisfied with only a small portion of theravada but when I see in my locality, it's the mahayani and other similar religions who wins my emotions by showing so much generosity by helping poors, providing free food, free medicines etc. whereas theravadins remain buisy in free abroad travelling and this becomes a greatest learning for me without the need to even look at mahayani texts or of others.
Is it possible for individuals to use different concepts and arrive at the same goal even though those concepts are misinterpreted by many people in both schools?
As far as practicality of life is there in this modern world, mahayani wins over this race also because of it's vast support in every direction and for almost every type of person(even for the bad-asses, there is tantra way to deal with them as per mahayani texts). Even if this tantra way might not be approved by theravadins, still end purpose of this way is only to change bad behaviour of bad••• ones ,i.e. enable others to have an 'insight like in theravada'.
What can those following the Mahayana learn when studying the Theravada as the Theravada see it?
Still, when it comes to the fastest way of rectifying defiled behaviour pattern within, it's the Theravadin way as in this, we directly deal with the behaviour within our body by temporarily ignoring outside world like various types of Vipassana, whereas in Mahayani way, one may take vows to rectify outside world temporarily, like here --
even these vows might differ & hence thereby increasing samsara cycle. Still, end goal is same ,i.e. to get enlighten and help others too.
::::::::::::: That's All for now ::::::::::::
Can Mahayana and Theravada learn from each other?
Learning never stops till enlightenment.