(If this should go elsewhere...sorry...) For the past month I have been working on this humble offering:
Just as a disclaimer...all this is based off my own research, using what are sometimes, at best, dodgy sources. Where possible I have tried to use census data, but this isn't always possible or accurate enough...so I've mashed it together. The map (should) show where languages are spoken in everyday life - thus why some languages are not present, or occupy a smaller area than that of where they are spoken.
As this is a work in progress, if anyone can make this more accurate I would welcome it!
It would be a somewhat difficult challenge!