I studied linguistics in college but never used FLEx. Sounds like an interesting project. Why do you say it's not very good (outside being windows only) and what keeps you from starting this project?
re: Problems with flex - the issues are laid out really well in a recently paper! Here's a bluesky thread from one of the coauthors with a link to the pdf: https://bsky.app/profile/amaliaskilton.bsky.social/post/3lgq...