Very nice alphabet! I always found Ogham really interesting and think it's a pity, that you rarely find anything like this in fantasy settings (in contrast to the widely used Nordic runes).
Having the Irish translation on the map as well would be interesting - perhaps you just have to try and see if it seems too cluttered. I'm also not so sure about the Japanesey look and the rectangle looks quite harsh compared to the soft lines of the hand-drawn map. Perhaps it would work better with rounded edges.