CT often refers to CoolType, Adobe's basic font technology that usually hides behind wrappers but can be found with some "ct_" opaque structures.
AGM (Adobe Graphics Manager) is the engine for primitive drawing operations following the PDF/Postscript drawing model.
There is no comprehensive official documentation for assertions that I know of. Some years ago we had an inofficial wiki on the private web site of Mark Niemann Ross, but when he left Adobe he also pulled the plug on that wiki. It was anyway only half-heartedly maintained by too few volunteers.