Seeing your thread I honestly just thought it was an uncommon name. I don’t associate it with those words myself. I think there are similar names out there that makes Gala feel vaguely familiar and not at all strange. Names like Gale, Gal, Galina, Galen, Galilea, Gali and names with similar endings such as Calla, Ella, Carla, Layla etc. It’s super simple to spell and pronounce too. I think it’s worth keeping on your list.
I’m Australian and I don’t think I’ve ever heard someone actually use the slang term flamin’ galah. I didn’t personally think of that. If it’s a person’s name, I’d very easily accept it at face value as a name. The syllable stress is different in any case.