Ehe, a c has been lost, indeed!
I made a sad discovery, Goyyah was right, Notepad++ needs to be recompiled too.
While the stylers.xml and langs.xml files looked like the program was flexible,
looking in the sources to see why I didn't saw AutoHotkey in the language menu (as shown by Goyyah), I saw that author, for some reason, hard-coded the language lists in several places!
I don't understand this choice that forbid using less common languages already supported by Scintilla. Being more flexible wouldn't cost probably much. Of course, replacing its SciLexer.dll by a standard or customized one might break some features (perhaps the line draw mode, perhaps the user defined one) and would bloat it (since this is a subset of languages, it is smaller than standard one). But I am still disappointed.
Well, perhaps you can petition the author:
1) To be more flexible;
2) (more likely) To support AHK.
I still have the above XML files, in case they become useful someday.