Hmm. I am a bit torn. On one hand, I fully understand why you did the "has to end with" part. On the other hand, for %d that feels really odd.

Maybe we should do something like: when it ends with #, or something. Purely because anyone who understands %d would not expect it to only work at the end.

That all said, for sure this PR misses a change in documentation for the console command, mentioning this. Otherwise only those who have seen this PR know that this is now possible :) Mind updating the docs for this console command?

I've added a documentation string to the console command - are there other places in the code where the screenshot command is documented?

What do you think about using an actual date in front of each "screenshot" or "Donnington Transport, 2037-08-20"? I mean something like this:
real date + hour + screenshot / company name, game date that is for example: 2022-05-09 23.28.37 screenshot or 2022-05-09 23.28.37 Donnington Transport, 1950-03-28. In my opinion it would be useful also in case of all other screenshots made by players. Thanks to this, it would be easier to keep the chronology in the album and thus find the photos you are looking for. The history of the game would also be created in this way. For server and automatic screenshots, this can also make finding events easier.

With screenshot numbers like #1, #2, #3 ... #287 there may be a problem that if you remove the middle positions, the newest screenshots will most likely have the first free name, which will destroy the chronology. This problem existed on Sony phones and, until recently, on Windows as well. This is obviously a different use, but the experience was really terrible. However, if you want to keep this form, it is worth making sure that each subsequent screenshot never uses a number lower than the last one.