Pronounciation depends on the region you come from but its more like Ishke bah-ha.

Bo(/)na na(/) Choro(/)in. ((/) to indicate an accent on the previous vowel) would be collar nor crown.

Bóna ná Choróin
Script with fadas added by Mud leprechuan

Gall is a general Irish word for foreigner and could have a similar meaning as the romans had for barbarian. I've never heard a noun that meant Barbarian as suc but there is an adjective barbartha so duine barbartha (dih-neh bor-bar-tha) would be a barbarian person or cine (kin-neh) barbartha would nbe a barbarian race. Barbarthach (bar-ber-hoch) or plural Barbarthaigh (bar-ber-hee) would be the form a noun from this adjective would take, but I don't think I've ever heard the words used.