Hi!
In French Wikisource, we have some templates already rewritten in lua like:
https://fr.wikisource.org/wiki/Module:Header_template The header template use by Proofread Page
https://fr.wikisource.org/wiki/Module:Classement Create clean default DEFAULTSORT
https://fr.wikisource.org/wiki/Module:Table for TOCs
https://fr.wikisource.org/wiki/Module:MathRoman : outputs roman number.

For commons, the issue is that, as I know, Lua doesn't support internationalization very well (but I think it could be done with some hacks).

Thomas

PS: I've also rewritten for French and English Wikipedia the Authority control template. It supports validation of some ids and fallback to Wikidata. See https://en.wikipedia.org/wiki/Module:Authority_control/sandbox and https://fr.wikipedia.org/wiki/Module:Autorité . The "fallback to Wikidata" feature is live on the French Wikipedia but not on the English one. I can help to adapt it to other languages.