Although I wasn't sure about creating this; this is not a request, but a suggestion. In welcome.py script of pywikibot, we have RANDOM_SIGN variable storing page titles per project to pick up a signature randomly. I didn't look at the history to see how old RANDOM_SIGN is, but in my opinion we don't need to extend the file and have another configuration variable, but we can directly get signatures for all projects from Mediawiki:Newusermessage-signatures. I did a quick search and found that the page is already created on arwiki, ckbwiki, fawiki, urwiki and zhwiki but not in enwiki and others registered in RANDOM_SIGN. Extension:NewUserMessage is the story behind this mediawiki page title. The extension is not required for "welcome.py" script, but just uses the page title. Some wikis installed the extension and finally we use that resource; killing two (or more) birds with one stone.

One more suggestion is that we can make the Mediawiki page title default to those projects want it or has no specific page for this purpose or don't want to register. Thanks!