I recently built this from source on FreeBSD. I only encountered two problems. One was a missing #include in configure, already patched in the FreeBSD ports tree. The other was that my termcap entry had a @8 capability, causing ncurses to yield a key code that yash didn't know to recognize. I posted about it on the Fediverse, and the author rapidly fixed it. There is at least one shell that's being actively worked on in 2023.

I also figured out why man on my not-quite-current version of FreeBSD cannot display Japanese manual pages, and fixed that too. LC_ALL=ja_JP.UTF-8 man yash now works. (-: