- Coq

- Unison

- Inko

- Gren

- SkookumScript (https://skookumscript.com/)

Also the many tiny hobby languages posted on https://www.reddit.com/r/ProgrammingLanguages/ and sometimes to HN/Lobsters.

You could add a feature that, every time a language isn't recognized, it's saved and the user can submit a URL to prove its existence.

- Algol : https://fr.wikipedia.org/wiki/Algol_(langage) - VHDL : https://fr.wikipedia.org/wiki/VHDL

I mean, it's fun, but it's missing at least these:

Z80, 6502, M68K, sh, csh, fexl, snafl, algol, PL/1, Z, C99, ForTran99, ...

It recognises bash but not sh or csh.

Still, a bit of fun.