Breton is is a Celtic language spoken by some of the inhabitants of Brittany (Breizh) in France. According to Ethnologue over half a million people speak the language.
There is an organisation that is actively promoting the Breton language. I am really happy to inform you that they have taken the trouble to localise the system messages of OmegaWiki and have started to add translations in Breton. I have send a file with many of the languages that are in the ISO 639-1. This combination will localise most of OmegaWiki in Breton.
The argument that proved convincing is that you get all the information we have. By steadily increasing the translations available in Breton, the experience will improve.