Ar diol: bróga leanbh, níor caitheadh riamh
It's a pity that you need one more word in Irish. Great translation nonetheless! :)
would grow up be a good translation as well in that context?
Fás aníos or fás suas would typically be used to translate “grow up”.
Why not Níorbh?
Why would it be "níorbh"?
That's a genuine question - what do you think "níorbh" means, and why do you think it should be used here?
Níorbh isn't a form of níor used before a vowel or before fh, then?
The níor in this exercise is a negative verbal particle - it is negating a past tense verb.
níorbh is a form of the copula is.