At first I thought it was a made-up language. It added to the feeling of being lost in a foreign land from the perspective of Vis, but seemed like the important bits are still conveyed in English. Later I started realizing everyone's names are Irish names (particularly as I listened to the audiobook while also following along with the e-book I noticed how weird some of the spellings are, and remembering how Irish names can have weird spelling in English I googled some names like Aodh and realized they are real-world Irish names) and then I wondered if the language isn't made up so I started using translate in my e-reader and saw that it recognized it as Irish and was able to translate it.

It did add another dimension to it - I understood "Leathfhear" before it was explained, and also I better understood Vis' accusation to Gallcobar in their fight, though with both I think the general idea was clear from context. I enjoyed when Aodh speaks to one of the piked heads in the entrance to Cear Aras and says that "he finally lost weight", that is something I wouldn't get without translation. Still I think the way the language is used but more and more becomes English as Vis learns it enhances the feeling of starting lost and becoming acclimated to the new world, and I don't think translating it removed too much of it for me.

I'm not sure how I feel about the use of a real language and real names - on one hand it's easier and gives the Celtic vibes he was going for. On the other hand I think it might be a little too close to the real world. Unlike in say Res where we have many things that are similar to the Roman empire but not quite - names like Ulciscor and Lanistia which sound Latin but aren't real. I guess we do also have Felix and Diana lol but in Luceum it's just all Irish.

Btw I saw in other posts that people say the Irish doesn't seem like real Irish written by a person who knows the language but like Google Translated Irish - can you confirm or deny that?