It’s fascinating how much better the search results are since I created a relation for “La Seymaz”. Before there were several partially relevant parts .. now it’s just one way. This avoids the problem called “Klickibunti” in Germany (thread). There still two more results, as I forgot to add them.
The Nominatim is at least partially configured to work well with relations. So the problem seems to be mostly not a technical issue.
