It did look wrong to me. A friend called Harrington confirmed that the translation of his name was O hArractain. He had heard of mid-Cork translations to O’hUrdaill, which did lead to an interesting blog which has many variations on translation for Harrington.
That page explains a term I heard for the first time only recently -“cliamhain isteach”
However, no luck on Urdalaigh
UPDATE 20130409
Cork City Council library site has translation of all Cork streets and they have:
Harrington Square Cearnóg Uí Arrachtáin
Google Maps has a further different translation:
Cearnóg Uí Úrdail
So much for consistency…..
UPDATE 20130411
For some reason Harrington Row, which is opposite Harrington Square on Ballyhooley Road has a different translation.