Adresses in bilingual areas

Hello! In some areas of the world (e.g. Wales, South Tyrol, Carinthia, Lusatia etc.) there are municipalities which are bilingual. In those places not only places, but also streets bear two names, so that adresses depend on the language you use. Is there a possibility to tag this situation? We have addr:city, addr:street and so on, but how to tag an adress in two different languages? Any ideas?

I would put the most used name (probably the one in largest letters on the sign(s)) in addr:street=. Then I’d put all the variations into language specific subtags like addr:street:en=, addr:street:cy=*, etc. Same thing for addr:city, addr:city:en and addr:city:cy

This seems to follow what I read at http://wiki.openstreetmap.org/wiki/Multilingual_names (look at the addr:street:= samples).

This is not widely used, but there are a few thousand occurrences of addr:street:en (often found with addr:street:ru, so I guess this form is more common in Russia. http://taginfo.openstreetmap.org/keys/addr%3Astreet%3Aen#combinations and there are even a few already tagged that way in Wales: http://taginfo.openstreetmap.org/keys/addr%3Astreet%3Acy

Ok, that’s exactly what I thought about. Just didn’t see it on the “Multilingual names”-page. Does Nominatim recognize those tags?

Yes, nominatim recognizes those tags.
Please note that in Brussels all streetnames are “name:FR - name:NL” (or “name:NL - name:FR”) and that they have tags name:nl and name:fr as well.