Assume your reference is [this](https://geany.org/manual/dev/hacking.html#filetypes-configuration-file), it doesn't link.

Hacking (and Makefile.am) is for working on Geany source, so you need to get Geany source. An install from a distro won't have source.

But the section I noted above is for adding a builtin filetype, needing code changes in Geany (which you would not be able to make without source anyway) not a custom filetype as discussed in #3232.

So I suspect this is not what you want to do.

Yes Ubuntu LTS is well long term stable, ie it doesn't update to newer versions, those go to the non-LTS first.

I assume you are still working on Awk. There is no awk specific lexer in lexilla, so (unless you write one) you are stuck using a lexer that is "close enough". So the only reason to add a built-in type for awk would be to get the ctags symbol parser for awk. I'm not sure how up-to-date Hacking is about adding a parser, probably best to examine any recent PRs that do it.

There is no awk specific lexer in lexilla

True. But a downstream maintainer has developed one (for GAWK, by the looks of it): https://github.com/zufuliu/notepad2/blob/main/scintilla/lexers/LexAwk.cxx

I think the original issue is resolved.