How do you determine where Welsh or Scots Gaelic is appropriate in your rendering?

I took a look at the German rendering library and noticed they embedded some shape data to assist in their efforts. This seems wrong to me: If you are rendering a geographical database (OSM) why should you need an additional geographical database to help interpret it?

Sure seems to me that OSM should have a way of specifying the default language(s) for an area, maybe some tagging on the boundary (multi)polygons.

All this because I tried using my style for making print maps in Nepal and was astounded to see that there were nearly no names in Nepali.