I finally got the latest version of this mod but I haven't played much of it yet.
Anyway, it appears the new "extra Wights" on the Necromancy spell through higher levels / Black Portal don't follow the normal placement for those summoned units. The first Wight appears where it should (by your hero or, if near a Black Portal, the Black Portal itself) but the extra ones appear randomly in one of the corners of the map - just like the Shadows through the Illusion spell that summons them.