The reason I want to do it this way instead of saucing each image is because some of the images are very old and disappeared after a while and can't be reverse sourced..
@coyote hmmm and you want to get like the url of the profile of said artist, right? not exactly the url of the original source because it may have disappeared?, if i understand correclty
@coyote uuuh what i was gonna say is that Gelbooru has a the Wiki section where you can check more info abouit a given tag
https://gelbooru.com/index.php?page=wiki&s=&s=view&id=7801
the problem here is that it seems that the wiki does not have an api endpoint so....
Maybe you could try seeing if you get a different sauce by parsing the saucenao result?
@coyote to be honest i think the most plausible solution would be to do a lot of comprobations on other existing images of the same artist to see if those images are live and then extract the profile of the artist by parsing the page (and then caching the result in case it would needed to be done it again)... at least that's how i would do it with numi
@coyote i have a image posting bot on twitter, and people had been requesting it the source of the images since a lot of time, but there was that problem that sometimes the profiles had disappeared or the source given was an image LINK and not the page of the image.
I just did it the lazy way, i just included the name of the artist (the gelbooru artist tag) and the url of the source (as long as it is NOT a link to an image itself) and if the link it's not live now well... not my problem 
at least they now have the name of the artist too haha
@coyote there's this code that a bot on twitter uses to get source of images (much like numi does) and also posts the url of the profile of the artist, you may want to give it a look
https://github.com/FujiMakoto/twitter-saucenao