Heroes 5.5 WarGame Edition - Tactical Edition.

The catapult is too powerful...

Considering the game length for which Nargott is making this mod, it's not that excessive, but yes – I would slightly reduce the percentage.
Assuming that rounding is done downwards, Tier 7 will lose one unit only if there are 5 or more units, and WGE is designed for a game length of approximately one month, so it is most likely that Tier 7 will not be affected or will be affected by only 1 unit, and these perks will have the strongest effect on Tiers 1-3.