JOSM: problems reading characters with accents in CSV file

For the dutch public transport I make a list of busstops from the open NDOV files which I present in CSV to open in JOSM. There are characters with accents in the file, like ëöü and JOSM displays the replacement character instead of the accent characters.
Is there a way to get these characters displayed correctly?
The files are basic 8-bit iso-8859-1 files.

An example file can be found here:
The name should be Italiëlaan.

I would try with converting to UTF-8. There’s no way JOSM can know what encoding you are using just like that, and iso-8859-1 hasn’t been a sensible default for a long time now (aka at least a decade).