Lughaidh,
I don't know if you've seen this on gaidhlig-b,
https://listserv.heanet.ie/cgi-bin/wa?A2=ind9703&L=gaidhlig-b&P=13834 quote:Ann an Uladh (Dún na nGall), cluinnear "Móra dhuit" agus "trathnóna
(feasgar) maith" uaireigin, tha mi creidsinn.
In Ulster (Donegal), one hears "Móra dhuit" (good morning) and
"trathnóna maith" (good afternoon, evening) sometimes, I believe.)