First of all, I'd like to thank you for bringing us fans of the Diablo saga (particularly DI and DII) this top-notch modification. This mod has added plenty of replay value to Diablo 1, and it is exactly what this 1998 classic needs.
Now I have not found any bugs except for dialogue ones, which does not jeopardize the overall quality of the Belzebub mod. However, these bugs have made the overall experience rather difficult sometimes, especially when it comes to Griswold. Tristram's Barmaid (I cannot recall her name at the moment) crashed the game for me if I spoke to her at the very beginning, but after a couple of quests, this bug is gone. Unfortunately Griswold is a different story; if these dialogues crash the game, one will not only not acquire the quest but not be able to repair (extremely useful for most if not all characters). Fortunately I was able to finally talk to him AFTER finding the rock-item he seeks, but I am nervous every time I talk to any of the citizens, fearing that my game will crash (and I will have to clean areas once again or stumble upon any other inconvenience).
Thanks again for all the effort put into the making of this mod as well as the others, and best of luck in all other endeavors.
[UPDATE]
I was able to fix this issue by extracting the diabat.mpq file from a different disc of the game itself. It is possible that the disc the diabat.mpq came from is a newer version, more polished, and perhaps missing the dialogue/quests and some other content that the company had cancelled before its release.
I recommend trying this out if anyone has issues with Griswold at all or any other npc, particularly for the Anvil of Fury Quest. Once I got to that quest, the game would crash if I brought the anvil to Griswold. The .mpq switch has fixed these dialogue bugs for me as far as I'm concerned.