At one time it was common for bands to give all members songwriting credits so they'd all have a share in the royalties. That's why you'll see songs credited to all members of a band in a database, liner notes or both.
In the event of a discrepancy between what's printed on the release, I usually give liner notes precedence over rights society databases. There are a limited handful of exceptions:
* Someone was found to be involved after the release came out. That's what happened with Ted Nugent's "Stranglehold"; Nugent admitted his former bandmate Rob Grange co-wrote the song but never received credit.
* There were allegations of plagiarism, and the plagiarized party's name was added to the credits. There are a number of cases in which this happened; probably the most egregious one I can think of is Michael Bolton's "Love Is a Wonderful Thing".
One thing to keep in mind: songwriting credits are often used as bargaining chips. Artists will often be given credit in exchange for making a guest appearance on a track, and in the case of tracks with samples the authors of said samples will often be given credit alongside the core work being performed in the track. (This last example is the likely reason you'll find remixes or other alternate versions being given their own entries in rights society databases.)
I know this is off-topic, but I have to clear the air on this.
Ace Frehley was never "too drunk to record" per se. In the case of the Destroyer sessions, he got frustrated from being under the microscope and started skipping out on sessions. He didn't realize at the time that that meant he would be replaced with a session guitarist.
I'm not aware that the "special thanks" situation you described ever happened on any KISS album. I do know that at least on Psycho Circus, the members of KISS were listed in the liner notes, as if to suggest they all played on all tracks on the album. (It later turned out this was not the case.)
This situation is not unique to KISS. Many other bands have used session musicians on their album, often uncredited.
There was no "20th anniversary edition" of any KISS album; are you perhaps referring to the KISS: The Remasters series?