Eh, we've heard from enough sources that have actually heard the material, combined with the leaks, that there are at least 18-20 songs from CD era that existed in some form with vocals
In 2006, Axl said they were working on 32 songs, 26 of which were "almost" done. Bach claimed to hear 3 albums worth of tracks which could have been an exaggeration but is in line with Axl's quote. Richard, Dizzy and DJ all commented on a couple albums of material existing after CD
Whether they're deemed worthy of releasing, or something that Axl wants Slash and Duff to rework, is another matter but
Silkworms/Absurd, Hard School, Perhaps, Atlas, Eye On You, State of Grace, Going Down, reworked Oh My God, Nothing, the cell phone recording of The General obviously all exist with vocals, so that's ten. We know that Soul Monster, Oklahoma/Berlin and Seven exist. Don't think it's unreasonable to assume there's another 6-8 "almost finished" songs from 2002-2014 era but again existing and being something that would be viable or of interest for the current lineup to rework and release is another story