As for unregistered torrent, that is a sign that the torrent has been removed from the tracker for some reason.

What do these errors mean? Are torrents actually removed from here? How do I start seeding these torrents again?

Thanks.

Since you tried to seed some torrents that you hadn't been seeding in a while, it is not surprising that a few were no longer available on the site.  Torrents I'm seeding go dark permanently every once in a while.  Often there are a few from the same studio, so it seems obvious why they are no longer available.

You could search to see if they are even still listed, making sure to include both active & dead torrents in your search.  You might also use Google to search the site including site:gaytorrents.ru as a search term because the search function here can be wonky.  Be aware that Google will also return results for torrents no longer on the site.

I always respect the fact that a torrent has been removed from the site and would not create a new torrent of it.  I just move the video to an archive folder.

Every once in a while, the server is down and a large number or even all of the torrents I'm seeding go dark, but that eventually resolves without me doing anything.  (I'm sure the staff is doing something, though!)  So I always give a dark torrent a day or two to make sure it's not just a temporary issue before archiving it.

I too have seen this issue, myself.

We don't support "scrape" because it causes too much a drain on server resources.  Very small trackers can do it, but it would cost a fortune to run a full feature server with as many members as we have.