Read moreTirnenn character names are a fusion of Welsh, Gaelic, Scottish, Irish, English and some onomatopoeic sounds.
You can read more here from this discussion thread on /r/wow
The names are corruptions of at least 3 languages, but I'll do my best.
Angwyrdmn = Angwyr means Angler, Angwyrd means angst. I suppose you'd have to look at context to figure out the actual meaning for this one. If he's a fishing trainer or vendor, it's safe to say its meant to mean Angler. But Angst could also be the one, because I can't find a single translation for what "dmn" might mean, so it might just be a corruption of the English "Damn". Giving the NPC the name Angst-Damn. Which would also make sense.
Groonoomcrooek = This isn't Welsh, but could be Gaelic, as they use sounds to describe things sometimes. In this case, this sounds like a toad croaking doe...
Tishereenelee was a solid runner up for "most easily pronounced Tirnenn name" but the competition for "least easily pronounced Tirnenn name" is much more interesting lol.