"She has a long nose."
Translation:Tá srón fhada uirthi.
Ar + é = air
Ar + í = uirthi
And it's the difference between 'big nose' and 'long nose'
Sorry - I wasn't clear. My problem is that DL accepted srón fhada uirthi but rejected srón mhór uirthi. Then did the opposite for "air", i.e. rejected srón fhada air and accepted srón mhór air.
Was it for the same translation? Was it 'long nose' for both, or was one 'long nose' and the other 'big nose'?
I think it was long nose for both - but don't remember at this point. There were a lot of problems with that section - "ag" versus "ar" needed correction.
Committing the individual words to memory won't help - in fact that's probably why you got this answer wrong in the first place.
Tá X aici normally means "she has X". But Irish doesn't use this syntax when X is a feature like srón or gruaig. When referring to such a feature, or to a medical condition or an emotion, Irish uses the preposition ar instead of the preposition ag.
tá leabhar aici - "she has a book"
tá srón fhada uirthi - "she has a long nose"
tá slaghdán uirthi - "she has a cold"
It's not quite that simple. For a start, these meanings only occur in combination with the verb bí - tá X ag Y, "Y has X", bhí X ag Y, "Y had X". ag on it's own doesn't imply possession, and even in a tá X ag Y sentence like tá fear ag an doras, ag indicates position - "there is a man at the door", not possession.
So translating tá X ag Y and tá X ar Y into English, and translating "have" into Irish rely on context. One aspect of this is indeed description/state versus ownership/possession, but that isn't sufficient to cover all situations, and sometimes you just need to be familiar with the traditional usage in both languages.