I think the yeshivish world is more insulated. Although baalei teshuva are accepted, there is a general apprehension with the possibility of influence from the outside (except with Chabad). I think the modern world is generally less concerned about people from varying backgrounds, as long as the current committment matches theirs. There are, however, Sephardim in the modern world as much as there are Ashkenazim.
If, Brooklyn Sephardim hold by the Syrian edict, than that group will include the modern Sephardim as well.
So, it leaves you with a few choices: 1) find a shul that embraces baalei teshuva and gairim and choose your place based on that, not on it being Sephardic, 2) move to an alternate area that is known to be more open and embracing, 3) ride the storm and make your own way by finding your own individual friends, schools, etc which you then make into your community.
I know a family who is facing the same challenge you are who is following the third option (paving their own path, looking to those who are accepting on a one by one basis).
It does sound like your perspective matches values in the MO world. However, there are wide ranges in levels of observance. There are people who call themselves modern who are not as careful with mitzvos( tznius, kashrus (they’ll eat salads in treif restaurants), negiya, etc). There are also people who call themselves modern (because of their openness to secular study, their willingness to interact with the world at large) yet are equally as machmir on shmiras hamitzvos as those in more traditionally right wing circles (careful with tznius, taharas hamishpacha, kashrus, and may not only set aside time for learning, but might learn in kollel after marrying).
It could be confusing navigating the modern circles when you’re seeking your place. There are so many shades of grey (women who love learning Torah and choose to become rabbis, women’s davening group, where they not only daven together, but actually have women layning). These are just some nuances to be aware of. The more you know yourself and your values (in detail) the better you’ll be able to find your place.
I understand that it’s incredibly difficult. H’ should guide you and help you find the best place for you with much ease.