Oh hey! If we're using fictional languages in-universe, then I'll be using Sylvan since y'know, Fey-people. From a meta perspective, it'll use Gaelic words and phrases, preferably Old Gaelic, but I'll not be able to tell the difference anyway.
Hey! That sounds great! It would be really helpful if there was a transaction also included with the language so I'm not rooting around in a Gaelic translator for hours. xD