I've continued playing and have been loving the new addition of Meph's tileset. It's always been my favorite. Great job on integrating it!
That being said, I've noticed one thing that seems a bit extreme. Imps seem to frequently spawn in the top layer of the cavern. To a point where I've been hit by a giant herd of them within the first year every time I've ever gone to the cavern layer. They climb like nobody's business and will always find their way into your fortress or near where you've started setting up. I'm always down for early fights against tough enemies in the caverns (Had a troll find its way in and had to fight it off), but imps seem a bit over the top. I know they throw fire in the games, but fire in Dorf Fort is a much different beast. Any dwarf hit by it is more or less guaranteed to die. On top of that, the underground is heavy with flora everywhere, so a single fireball will cause mass destruction on a borderline nuclear level.
I've gone ahead and removed their fire abilities on my end just to make things a bit less crazy (although they'll probably end up being ridiculously weak without it, I imagine). But as a recommendation, it might be better to put them on a lower cavern level so the first cavern level ends up being less extreme. Especially given a lot of embarks may need to hit it in order to get water ASAP. Either that or give them a ranged ability that is fireball in name only, but causes direct burns or something similar to avoid having true Dorf Fort fire hit.
EDIT: Also, just a side note, but Morrowind in the pregenerated world seems a bit too... Green. I was expecting something a bit more dead. But maybe there's lore there I'm unfamiliar with.