Any EA BF model will have a high vert count and because of JKA models have a limit of 1,000 verts per selected part of the model you are going to need to cut down the verts so they are below 1,000. Now there are some BF models for example like the Royal Guard that I think had a vert count just below 1,000 for the helmet that I was using, so for Kylo his helmet might not be that bad. Don't let high vert counts scare you though, it can be done which I have learned myself. Not sure how strict JKHUB is with ported content, but I really don't see it being that big of an issue if you got one of the already existing Kylo models sitting around in the files here and had the helmet ported since full ports aren't allowed in the file section. I have worked on TROS Kylo myself a few times, if you have discord just send me a message and I can see what I can do for you.