In Asia, people do free-fly smaller birds, like conures, IRNs, cockatiels, and even lovebirds. It's largely a matter of personal comfort level - if someone can accept the risks, then ok. Conures, of course, are more common, but it's doable with the right trainer mentoring the parrot and human. I say doable, not necessarily recommended - that's up to you to decide for yourself.
I have not seen a ff-ing blue crown, but that's because they're rare where I live. I have seen a couple of Hahn's ff-ing, but they isn't to say they're inclined.
I'd recommend you reach out to your local ff-ing community for a variety of reasons. One being that flying as a flock is generally safer, and the other being that they can give you better contextual advice for your area.
Since you're dealing with conures and mini macaws, from my ekkie-only background, it doesn't seem like much a difference since both are monogamous types (I only point that out because ekkies are not monogamous and Aussie ff-ers have found that they get lost more frequently than the other parrots).