[stumped]

your adobe Id was from the adobe web site ( possibly a reader device helped you get it ) it has nothing to do with your google account(s)
the single adobe ID can register multiple devices, e.g. a PC, a reader...

your simplest solution is to get the books onto a PC, if you can, [ by downloading with ADE which should still have that adobe registration, then strip all annoying and confusing DRM with the various tools from elsewhere
if you lost your adobe password, you may be able to recover it from adobe; they reset many accounts as they had a huge data security breach a while ago

BUT, AFAIK, a book you buy from google play is locked to the google account you bought it with, and can only be read in the google app, so your troubles and confusion may not yet be over