Cool - well OpenStreetMap is super easy to use but by default you get the names in local languages not any one specific language. The pan zoom map uses tiles which has the map image on it and all of the text rendered onto it. So to change language you have to change the tile server to a different server or different tile set - which not many people do. So a few companies have produced tile sets done in different languages and the most popular are the ones in English, French, German, Spanish and a few more. But that link above does suggest that someone out there has done one for Scottish Gaelic so its a case of getting their tiles. Not sure if you have to sign up to their site to get it. But if that does work then you have all of the world all done for you.

Its likely that a specific small area of the world is not very well covered and if you find that for your own area of Cape Breton then you could make a map up for that and populate the names for it which is a whole lot easier than doing the whole world. If you did that then its best to use some kind of paint package like Photoshop or similar and keep the names of places on a separate layer so you can edit/add more names to it.

That being the case your task falls into two parts. One, get the base map and two, put all the names in. I think the guild can help with 1 but 2 is going to be a job only you and a few others can do.