I don't think so, but I'm not 100% positive. I'm sure Geany won't recognize a new language added like this, but I'm not 100% sure you
Can anyone else confirm this? IMO this is an important point from the extensibility perspective. If a language is not supported out of the box you need to be able to configure both geany workhorses: scintilla and, in this case, ctags.
Or maybe ctags configuration could be done at the geany language level (filetypes.*) instead of at the system user level (~/.ctags). That seems the correct way to do it but also looks harder to implement. I don't know how difficult it is to initialize the embedded ctags with specific options or to instruct it to load some initialization file at startup.