osm.wiki/Bilingual_street_names
Finland is also described here on this page about Bilingual street names

Finland

Some cities/places/streets have names in Finnish and Swedish. Use name key for the commonly used language (mostly Finnish, use Swedish version if municipality is mainly Swedish) and name:fi and name:sv for the specific language version.

Up in the north there are also different (3?) Same names, but I have no knowledge about these. (yet)

More information on the WikiProject Finland page.

if you use the name:se and the name:fi tags and fill in both names there should be no problem.