Greasy Fork is available in English.
It preserves YouTube's progress bar always visible even if the controls are hidden.
< Feedback on YouTube ProgressBar Preserver
I agree, it would be so great to also see the SponsorBlock segments... unfortunately it looks like the userscript has been abandoned.
Thanks for confirming SponsorBlock doesn't work. Very important observation and unfortunate situation.
just so you know, this script is not compatible with an add-on called SponsorBlock
here is a video example you can test it out and see that the SponsorBlock color-bars don't show in the progress-bar preserver.
dunno whether anything can be done to fix this, but I just thought I should let you know!