That’s exactly what I use, works like a charm.

You never own any game, unless you code it yourself. You might hold a CD in your hands, but the game is still owned by someone else. You only have the right to use it as noted in the license you agreed by purchasing it.

Short answer: Not enough bad reports, compared to older good ones.

Long answer: ProtonDB only takes the latest report of each reporter into the rating. Which means if old reporters come back with a negative report, it will shift the rating quicker, as if only new negative appear.

This game is in a situation where it got a lot of good reports, and in the last 6 months there were less than 80 negative. But the trending tier is already bronze. Probably needs just a few more reports to give it the last push. You can also see in API answer, that the confidence of the good rating is strong due to the many good reports.

Nope, response by a proton dev was

Not ready yet