T384709 would be good to do first as well to simplify it.

Having dived into this a bit, I am questioning the premise that having a non Lua template is "simpler", just because actually the templating language leaves a lot to be desired.

Both require an additional extention: the ParserFunctions extension if using the templating language, and if we were to do this in Lua, the Scribunto extension. But it's not really possible to write a functional template without either ParserFunctions or Lua. And IMO Lua is more human readable. (cc: @DLynch).

The main way it is more complex is then it does require two pages, the Template: and the Module: page, whereas it's more obvious where the code for the template lives when it's actually on the Template: page. So that is a clear example. But when it comes to users modifying the template for their own use, Lua might actually be more user friendly?

I guess the main argument for it being less-friendly is that it does require a hypothetical completely-non-technical user to learn a new thing. We can assume that to do wiki admin stuff you're going to have to learn wikitext, but you could quite reasonably do everything on a wiki without ever needing to learn anything about Lua.

Personally, I think Lua is super-easy to learn, and is certainly more user-friendly than writing conditionals in wikitext, but that might be me feldspar-and-quartzing the situation.

In discussion with other folks it was brought up that many non-english wikis will copy paste templates directly from en wiki, which means that a requirement of such a template might also include that it is compatible with en wiki, which I think is a really good point.

That is possible, but it does make it harder!