(Although, part of me is also uneasy with that idea - using someone's culture & heritage as set dressing, without paying it any of the actual respect it deserves. It would be just as easy to copy a few paragraphs from Wikipedia, & use a Star Trek font to make something look fantastical, which is something I've done in the past.)
I don't know if I agree with that, but I will say that people in general deserve respect. If I were playing with an Irish player, I definitely wouldn't want to offend them by treating their language like set-dressing, and I wouldn't particularly want someone using my culture for that, either.
Sure some people might be offended, especially if you're an asshole about it. But generally Irish people are glad to share their culture, and delighted to see genuine interest from foreigners. Sad though our history is, we don't have the kind of issues that make some other groups more reluctant to share the symbols of their identity†.
† Notable exceptions apply, especially regarding English upper classes.
So, thanks for trying to be cool about this stuff!