The version of SQ4 that has the debug code is a beta that was leaked from Sierra about six months before the game was actually released. It was distributed by a cracker group known as The Humble Guys (hence the "THG" in the debug help file that was posted). I know this because I managed to get my hands on the leaked and pirated beta a few months before the game was released in 1991. Unfortunately, I deleted the beta as soon as I had bought a legal copy of the game. The things I remember about the pirated beta were the debug mode and the fact that the game was very buggy and crash-prone.
Exactly... Since it wasn't the final sales release, most people probably deleted it... I'm aware of the whole THG/INC/etc. scene at that time and managed to get some savegames (by INC) of the beta... However, they contain the same version number my version has (1.052)...