Make sure you repost your request in the feedback channel, so that Apple will see it and not just the other users in this forum:
I don't know for sure whether the extra characters required for Maltese (ċġħż) might all be available in the layout for another language or not. It would be kind of tedious to check. But there are a couple apps, Unicode Map and UniKey, which let you create a sort of custom keyboard layout using any Unicode characters which can be used for copy/paste, etc.
You should also search the app store on Maltese to see if anyone has created a keyboard for that for copy/paste or email, etc.