I'm in a retro-game preference mode right now. (MM6 and 7,
HOMM3, Civ4,and most recently Bard's Tale, which has been remastered to include segues to BT2 and 3.) I haven't played MMX for awhile, but it's still in my library, so I'll start a new game and see what I come up with. Unfortunately, I never drew any maps for X, since the automapping was so good in it.

I don't remember at which stage in the game you enter the Sacred Grove (or even quite where it is. Is it supposedly reachable from the original "land" map, or does it require going to the teleporter over by the first castle? If it does, it may take a few days until I get there.)

I'll give it a go (in between BT1 sessions--I've just about cleared out the wine cellar/sewer dungeon.

And yes, my computer crashed a few times during my various play-throughs, but like you, I was able to finish the game (with every combinatiion of characters. I have one of the oldest versions of Win10--I wonder if that made the difference in playability of some games that a lot of people couldn't finish because of impossible-to-fix bugs?)