Strawberry is super confusing with playlists. Out of caution, I have learned to save Playlists multiple times to a file and try to close them all before opening/playing new stuff.
Too many times I’ve experienced selecting something new to play not only replace the currently playing, but replaces the Playlist, and it seems to overwrite it immediately.
I use custom categories for my games, both to categorized the style of game and also mark completed ones. You can add to multiple categories.
I also use the hell out of Steam Notes per game, which supports markdown by the way. I use it to note things I’ve played elsewhere, or unique notes about setting up a game to play, custom settings, or stuff to remember if I don’t come back to play for months or something.
They generally sync between my Deck and PC too.