I know Maud was learning Irish. Does anybody know if she'd written something in Irish or how good was her Irish?

No idea, but I've read a short passage from the diary of Douglas Hyde (in Irish) in which he describes giving Maud lessons in Irish, how they drank and got Merry and how boring they found Yeats :-)

I think I have the passage in a book but not here at the office, I could check when I get back home.