I’ve put all the end credit pages together again with the deciphered codes. Things we’ve been able to work out so far about it-
1. The top bit is probably going to be a picture of Grunkle Stan (if that is his real name).
2. Unlike Dipper’s Guide to the Unexplained, the codes don’t seem to be making up one coherent message.
3. Yes, that last one is Sailor Moon reference.