MMH5.5 - Герои Меча и Магии 5.5

-combat skill retaliation bonus reduced to 10-20-30%

It is very weak bonus, equal to +2.5-5-7.5% to melee offence, because only 25% of melee damage is retaliation damage.
You can verify this claim by looking at recordings of any fights and comparing the resulting retaliation damage, and the total melee damage.

Добавлено через 8 минут

• Leadership can now buff initiative of undead creatures, mass spells are significantly more powerful and combat is nerfed.
• War machine HP now scales with hero level (if you have the skill). 

 

1) 3-6-9% ini boost is equal to 1-2-3 morale, but this effect consists of 2 components: first turn, and later turns. Standard leadership doesn't boost first turn of units, but necro leadership boosts. It means that with this skill, the undead will be ahead of the living on the first turn but slower in later fight.

2) ideally, basic HP should also scale with hero level - but I understand that this place must be additionally searched in the exe file

-retribution skill buffed from 2% to 4% per morale point

Surprising change as your mod is heading towards weaker stats and perks, while the 4% retribution is an extremely powerful perk even by the standards of the original, up to +20% non-retaliation melee and ranged damage, that's more than many expert skills for 3 levels.
This perk at 4% per morale has value of 3-5 of original stats (5%).

-logistics also gives tier1,2 or 3 reinforcements every week depending on mastery level

It's very good that you make logistics more combat skill. But extra forces is a rather boring bonus that does not affect the course of the battle in any way.
In my opinion, there is a more interesting alternative for logistics - this is a bonus to the starting ATB of units (5-10-15%, for example).
Moreover, you have already partially gone in this direction, increasing the initiative of the troops (undead) for leadership.
Necro leadership I offer a little differently: +5-10-15% bonus to initiative, but -5-10-15% penalty to the starting ATB of troops. In this form, this skill will be as close as possible to the natural morale, as it will not allow undead units to accelerate the onset of the first move.