Tag for CGIs used as coin pictures

Can we get a tag 'CGI' that can be used to identify coin pages that use computer generated images (mostly used by mints to promote no yet minted NCLTs) so we can filter for them and try to replace them with pictures of the real deal?

No such tag, these are not intended for such use (CGI, missing-pictures, missing-mints, etc.) but for content-related information (about the coin, the event, the person/item depicted, etc.).

You could put CGI as the source of the image ... but then we would still need a function to search image sources (this heavily bumped suggestion: https://en.numista.com/forum/topic112433.html).

Regrettable, it would have been the easiest solution that doesn't need any changes to Numista on Xavier's side.
All the other functionalities you've mentioned we can do by filtering for 'missing' ... no tags needed.

Even if CGIs are not "real" pictures they have arguable more of a claim for a copyright then simply photographies.
So we can't simply put CGI in the source but right now to source is most of the time some bullion peddler site that obviously doesn't have created the graphic but the mint (don't know why people assume some whole seller owns the right to a mint graphic).

Also like you've mentioned this wouldn't solve anything anyway because we can't search/filter for it.