Looking again at Brussels, I figured I would throw in another point of possible confusion: places that are the border between two language communities. This is not uncommon there: on one side of the road you would have Vlaanderen, where Dutch is the sole language (ignoring faciliteitengemeenten, iykyk), on the other side you have Brussels, where French and Dutch stand on an equal pedestal. In Vlaanderen, the name is just Dutch. In Brussels, the consensus on OSM is to tag the name French - Dutch. Roads straddling the border seem to use a similar approach…
However, Vlaanderen and Brussels do not necessarily agree on the official name of the street in Dutch. These combine the two (well, three) as either French - DutchBR / DutchVL or DutchVL / French - DutchBR, presumably whether Vlaanderen is left or right compared to the direction of the way. Some examples.
- Romeinse Steenweg / Chaussée Romaine - Romeinsesteenweg
- Vlaanderen Dutch name: Romeinse Steenweg
- Brussels French name: Chaussée Romaine
- Brussels Dutch name: Romeinsesteenweg (note the lack of a space)
- Chaussée de Buda - Budasesteenweg / Steenweg Buda
- Brussels French name: Chaussée de Buda
- Brussels Dutch name: Budasesteenweg
- Vlaanderen Dutch name: Steenweg Buda
- Avenue d’Itterbeek - Itterbeekse Laan / Itterbeeksebaan
- Brussels French name: Avenue d’Itterbeek
- Brussels Dutch name: Itterbeekse Laan
- Vlaanderen Dutch name: Itterbeeksebaan
I am by no means trying to claim that the current OSM solution is satisfactory, but I imagine literal edge cases are not happening only in Brussels.
Also, although Brussels seems to have settled on French - Dutch for street name signs, because it often works out that the French “cruft” comes before the name part and the Dutch comes after the name part (much like with French - English), this does not necessarily translate to other parts of society. An example I recently heard about comes to mind.
There are three main train stations in Brussels: north, central, and south. To make both language sides happy, the order of announcements depends on the station.
- North: Dutch, then French
- South: French, then Dutch
- Central:
- In even years: Dutch, then French
- In odd years: French, then Dutch
Now, I have moved halfway across the world, so cannot easily pop into each station to see whether the signs largely match that division, nor do I expect Central to be swapping signs every year (I truly hope they do not, then again, this is Belgium).
As far as I have gathered, this proposal seems to mostly use streets as an example, but does not restrict itself to streets. I am bringing up my silly station example because while an order might make some sense for streets, it does not necessarily mean that same order is used in all official capacities and signage.