Greta has two development paths: a default build designed for quickly eliminating enemies, and a chaotic one, which is even more effective because the Druid's Channel also buffs the Daughter of Silanna. Both options allow you to comfortably complete the Necropolis campaign.
So, there are no particular limitations in the upgrade path. They exist in terms of obtaining certain spells and moving around the map, but I've already explained that these are story-related limitations – we end up in an unfamiliar area, and we are pursued by a much stronger enemy – naturally, every mistake can be very costly. Of course, this concept may not appeal to everyone, but it is impossible to please absolutely everyone.
Regarding changes – I don't plan to make any changes to this map for now; I'm busy working on the sequel. More precisely, I don't have any ideas about what I can add or change. If anyone has any suggestions, please write them down; maybe I'll implement something.