along those lines, Zokka is a fork of elm that appears to be mostly dedicated towards bug fixes that Evan (the creator of elm) refuses to acknowledge or merge.

https://github.com/Zokka-Dev/zokka-compiler

edit: there's also Roc, https://www.roc-lang.org/, a language started by Richard Feldman who I believe was a former elm core team member. I think Roc aims to accomplish different things than elm, but definitely feels like a spiritual successor