Heroes 5.5 WarGame Edition - Tactical Edition.

Then the reanimator is a reaper, the reaper is a necromancer.

The Reaper is the most combat-oriented class, analogous to the Death Knight, the opposite of the human Knight (but instead of leadership, it's magic, and instead of light, it's summoning). The word "necromancer" doesn't fit here.
The Reaper kills enemies (reaps the harvest of death), the reanimator revives allies, the cultist/necromancer turns defeated enemies into undead.
In general, I don't use the word "necromancer" for a specific class, based on the fact that they are all necromancers (they all use this skill).

Agroila can be replaced with Wayer or Erazial (or did he kill him?)

Wayer duplicates the icon of Nibros, and Erazial is not in the manual at all; most likely, he also duplicates someone, or he simply isn't in the game.

On the maps, it is clear that Erling is a warrior.

A warrior specializing in magical units?

Necropolis: Arnel can be replaced with Anastasia's daughter from the sixth.

What's wrong with Ornella?

Instead of Shadia, Ilaya,

I like Ilaya, but she is fair-haired, which doesn't fit in with the Warlock theme.

Dwarves: Erling instead of Wulfsten.

We try to avoid transferring standard heroes to other specializations (from priests to ballista). Especially when the old specialization is not removed from the game, but is given to another hero (this would create additional confusion).

Humans: Isabel is alive, and Duncan, and another couple of red heroes; we can take the guy from "The Messenger."

We need specific suggestions for replacements here, because we have already reviewed all the campaign heroes. And we are not adding new heroes (more than 9 - 3 per class) in principle, so as not to multiply them for the sake of quantity, leaving only the best.
Duncan was even considered for Rutger's position.