I had a little look and:
https://support.last.fm/t/how-are-artist-and-other-catalogue-pages-created/410
It looks like last.fm imports their release data from a bunch of places, including Discogs and MusicBrainz, but also the streaming platforms proper, like Spotify Bandcamp etc
Not sure what this means, but presumably if it was imported from Spotify etc then editing it on MB won’t do anything.
https://support.last.fm/t/what-are-the-guidelines-for-correcting-artist-and-track-names/197
Last.fm uses MB guidelines for stuff but currently ‘cannot make corrections to their data at this time’ (from 2019 but couldn’t see any updates)
https://support.last.fm/t/how-do-i-report-a-release-thats-incorrect-or-missing-from-the-catalogue/211
This ‘how to report incorrect releases’ faq page manages to not mention anything about the topic 
Maybe @Bloopy has more insight?
My feeling for a long time is that last.fm is a bit of a sinking ship, definitely looking forward to ListenBrainz getting more features.
btw: last I knew a lot of the last.fm song pages are created on their first scrobble, and it saves the caps from that first scrobble. So wEiRd caps gets stuck in their system. It may be the same with accents, it might be unrelated to where they imported the data from. Again, unsure these days sorry.