Any chance this could be considered? Each citizenship could have two languages tied to it. You ask the clerk about (language) and pay a fee and can speak it.

You are a citizen of, say, Zoluren, but an Elf. Zoluren's languages are Olvi and Gamgweth. So you ask the clerk about Gamgweth, and can speak Gamgweth.

You can never know more than four languages (including Common), and you cannot drop languages once you've learned them.