Kneen has under Ballarragh Lonan - Derivation doubtful. Perhaps Balley-arraght, 'farm of the spectre or apparition.'

W W Gell in discussing wells has
Chibber yn Arragh. There are two roadside wells of this name in Ballarragh village, Lonan. As the Manx arragh, spring-season, is awkward to apply to wells, to Ballaragh, Bride (?), or to the earthen dyke on Snaefell known as Cleigh yn Arragh, besides its being of the feminine gender, recourse must be had to the Gaelic root ar, tillage, from which Joyce, iii., instances a number of Irish place-names, Arragh, Arraghan, Errey, Lisnanarriagh, etc. - an old Indo - European root, known to Cormac. Hence " Well of the (good) Ploughland."
wch may be the derivation for Ballarragh as well ?