This isn't the first time I've installed Morroblivion. A couple of years ago, I installed it too, the problem was the same back then as well.
I'm a huge conjuration fan and a huge Morrowind fan. I even helped navmesh some Skywind stuff awhile back (not that good at it, lol), and I'm fairly good at locating problems (I'm the creator of the Skyrim Crash Compendium on Skyrim Nexus).
But I don't understand why the Ancestor Ghost and other summons... well. Don't actually summon the Morrowind creatures, only the Oblivion ones.
Am I doing something incorrectly? I thought maybe it was a problem with meshes and textures not installing properly, so I extracted the contents of the BSA's into the Data folder. Same problem.
Now, I can't imagine you guys would create this and not finish the basest creatures and spells, so I'm wondering how to fix this situation.
Because it's impossible to
Because it's impossible to make new summon types without third party tools.
Look here if you want Morrowind spells.