I'll try and see if i can get this to work. Probably some changes were made to spotify that broke snip.
I have tried but sadly atm no. Changes need to be made to obs for that to work which im pretty sure they have thought of but have it very low priority on their todo list.
I wonder could you create a HTML file instead of a Text file with Keyframe animation code set to fade the text after 10 seconds.
Set the page up on the OBS Browser Source and it will run with CSS3 animations, at least in Multiplatform.
The only issue I see is when the page is changed, the updated song might not be reflected on the Browser Source without a refresh.
Could get around this with a forced refresh every so many seconds. The length of time before the refresh could be set based on the length of the song, determined before the HTML file is re-written on a song change.
This would then cause problems with when a song is forcibly skipped before the end of the song...
Other alternative is to just refresh the page every N-seconds or so but then you would need to check if the song name has changed every reset, so that would need JS and I'm not sure if the OBS Browser Source supports JS.
So it could work but it may take a smarter/less-busy dev than me to sort it ;)