[[Module:scripts]]

How do you mean?

We can detect if the input is the code of a language or a script, from its first letter. But by merging Module:scripts to Module:languages, lookup_language doesn't need to know that, so we can use lookup_language for looking up both languages and scripts.

I think we should rather focus on speed. lookup_language is a very heavily used function, so we should try to keep it fast. String pattern/search operations would slow it down. I know that it can be useful to make "smart" functions, but it's easy to overdo it...

I actually meant we should merge Module:scripts to Module:languages, the data in Module:scripts is relatively small.

So you want people to use "lang=Latn"? Huh?

The parameter's name can be changed.

That's not what I mean. If we add scripts to Module:languages, then a template like {{term}} would accept "Latn" as a valid language.

I see.