Heroes 5.5 WarGame Edition - Tactical Edition.

In other words, the stats should be comparable regardless of the changes.

And they are comparable even with 50% luck. The positive luck of a hero is not much less significant than morale. I gave the following ratings: 2.3% versus 3.2% (100% positive luck would have a weight of 4.1%). In general, all the advantage of morale comes from the fact that initiative is more important than damage; otherwise, there would be equality. The same ratio existed in Heroes 3 (only luck and morale gave twice as much bonus, but they triggered twice as rarely).

Added 1 minute ago

I will suggest another option: 50% luck, but remove the limit on maximum luck = 5; then you can kill two birds with one stone: the stat is useful, but it plays a weak role with small values.
In general, I probably find it difficult to discuss, as I am not familiar with all the nuances of the mod. But these are my thoughts.

The idea is good, but there are no visible possibilities for implementation yet. On the other hand, morale quickly reaches its limit if you don't mix armies; and even +1 to luck is fundamentally psychological (due to its initial neutrality), unlike +1 to morale. In my practice, I don't even see how you can reach the limit on luck, except with a strong desire. +3 for the skill, +1-2 for artifacts, and also temporary bonuses to luck. Maximum leadership, on the other hand, seriously suffers without mixing armies, making any artifacts to increase morale unnecessary.