Here is my opinion on the matter. If others team members disagree they will say it.
First of all, thanks for your ideas. I really appreciate community involvement in such matters.
We wish for more code review from the community!
Having more community feedback on code quality helps triage good and bad PRs. With more feedback we can also have a better appreciation of the need for new features and when it comes to bugs, we cannot reproduce everything and therefore NEED community reviews, in addition to testing.
Ultimately my feelings is that the whole team wants to ensure SFML keeps a high code quality standard. It's part of its 'personality'. That's why I suggest we request the final approval by a team member. My hope is that with more feedback this will go much faster as grey area in the code would already have been discussed.
Your suggestion for adding a tag and putting more light on those blocked PR is a good one, I think.
I've tried promoting a few of my PRs on the forun a while back. Sadly, it didn't work. It also adds some work. Maybe we should instead regularly advertise that people can subscribe to github issues if they want to contribute. But in any case, people can always open a thread for a specific PR and attract the attention of the community.
Regarding testing, community feedback is absolutely desirable, even required for most bugfix. When we have several people regularly accurately testing features/bugfixes we will be able to rely on them and therefore reduce the workload of the team member (so that we can focus on code review, merging stuff, design discussions, maintaining servers, ci and more).
It's true that we have relied solely on eXpl0it3r for the merging procedure, and that for quite a while. He's doing a fantastic job for sure. But maybe, eXpl0it3r, do you want other teamates to help? That goes without saying that other members should find some time for this as well.
Currently merging is done in batches to make rebating less tedious. If we merge a PR everyday or so, every other PRs need to be updated. So we have to find a tradeoff.