What I’ve done:
I wanted to create a new release based on this one:
https://musicbrainz.org/release/86f6a69b-7374-4805-9d16-1bc6bc214fd5 (same release group)

https://musicbrainz.org/release/570d8220-e558-423b-bdd4-21c4adcb7c84 (my new release)

As the track titles from booklet differ for my new release I wanted to correct them in track parser editor as I can use there a "find & replace" browser plugin.
I did a lot of changes for the track names and hit "Parse Tracks" button.

All changes I made got lost whatever I tried.

I found out that track parser takes my changes only when I disable "Use track lengths" and additionally remove all times (:) from the end of every line. Only then parsing seems to work.

Another issue was that tracks get reordered automatically. And that although there weren’t any track numbers on start of the line (and I disabled "Lines start with a track number" and "Use track numbers"). Therefor please see:

https://musicbrainz.org/edit/53218343

https://musicbrainz.org/edit/53225607