Heroes 5.5 WarGame Edition - Tactical Edition.

You have to run just to stay in place, and if you need to get somewhere, then...

Full speed ahead, yes.
Well, the problem here is with the expected value. Yes, this kind of gameplay is risky (you can get unlucky and almost fail), but the trick is that in 80% of cases, people still manage and defeat their more cautious opponents. Therefore, it is quite natural to rush as much as possible and maintain the pace.
In this regard, Nargott's mod might even be good because the game as a whole is geared towards earlier stages, meaning people won't need the favor of randomness to play fast enough and not lose every fourth or fifth game against neutrals. Well, that's what I'm hoping for.

Return the name "Rakshasa Princess" (instead of "Apsaras Rakshasa") - still debatable, more opinions are needed.

Neutral. "Princess" is clearer, but you're probably bothered by the fact that there can't be too many princesses (and that they are all from the same "royal family")? I agree with that.

Magical Unicorns instead of Mystic Unicorns, opinions?

+1

Return the name "Light Unicorns" instead of "Radiant Unicorns", opinions?

+1

Return the name "Dancers with Death" (instead of "Dancers with Leaves"), opinions?

+1, or replace "leaves" with something less fairy-tale-like and peaceful.

Berserkers instead of Spearmen (return to the old, more descriptive name), opinions?

I don't know... I like Spearmen a little more, perhaps.

Replace Archons (alt druids) with something (too epic, but the alternatives are too bland)?

I agree with SRD's "oracle" option.

Fiery/Polar Priests instead of Flame Veterans and Elders (the word "polar" raises questions, but there's nothing better yet).

I've already expressed my opinion.

Return Erls instead of Tauruses, Tursos, and others (despite the confusion with Jarls), opinions?

Against it, this always annoyed me in the original.

Return Succubus instead of Liliths, opinions?

+1

Lords of Chaos instead of just Lords, return the word.

+1

Return Skeleton Warriors instead of Skeleton Servants (but then the question is, how to distinguish them from the alt), opinions?

"Servants" is more interesting...

Return Ghosts/Specters instead of Specters/Lamias (despite the confusion), opinions?

Against returning them, but I don't like Lamias either. By the way, this is where you could introduce "lemurs," which were discussed in the context of another creature. Instead of Lamias.
Another option is phantoms (but it might already be in use, I don't know).

Not everyone Googles what a Dhampir is, return Vampire Killers/Vampire Lords instead of Dhampirs/Vampires (but leave Nosferatu, because Princes after Lords is nonsense). Although, for true vampire connoisseurs, I would suggest the lineup of Assamites/Ventrue/Nosferatu.

Dhampirs are terrible. How can you upgrade a pure-blooded vampire into a half-breed, and then back? It's nonsense. And the word itself seems to parody a vampire.
I like all the proposed alternative options, but the last one is the best.

Return Phantom Dragons instead of Dragons of Fate (but it's the alt model), opinions?

"Dragons of Fate" is better...

Return Taurens instead of Giants, opinions?

"Taurens" is better.

Inquisitor (hero class) instead of Templar, opinions?

+1