Hello,
Among the things that iin my opinion would update further the Edain mod is inserting more balance in terms of leaderships cancelling.
It is a very powerful tool, especially in multiplayer I guess but it has also a lot of influence in solo gameplay against the AI.
But this tool is an arm only for some few factions (which is wise), like Angmar, Isengard, Arnor but above all Mordor.
All the other don't get access to this super powerful tool that can make Boromir or Saruman with the Ring not so dangerous as they would be otherwise.
I like mostly how this is implemented by now, however I want to point at some elements that can badly influence the game in the current system of leadership cancelling.
THE LORIEN MINSTRELS
The most important example I think are the Lorien minstrels. I tested it by saving the game when a unit confronted a Nazgûl and load it twice afterwards with activating their leadership, and without activating it, and there was no difference of damage taken by my units from this Nazgul in both case, so I conclude that the Nazgûl cancelled my minstrel leadership.
I expected a different result because this leadership sounds like a spell leadership such as the Glorious Charge, rather than a standard leadership, I mean even visually, the units don't glow as usual but they are surrounded by music notes.
The Lorien minstrels have been nerfed some time ago, they grant only 10% damage and armor which is nice, but they take 60 command points and 500 to research and they unique purpose is activating their leadership, which they can't do very often, and if then their leadership can be deactivated, this destroys their only purpose on the battlefield, and its ruins the balance in my opinion.
I think they are technical to use and that's an interesting unit. To be sure they stay that way, their leadership in my opinion has to be not cancellable by any way.
FINAL STAND OF THE DWARVES
Here is a very interesting case of leadership cancelling. Using the Central Spell of the Dwarves in the Horde map of Helm's Deep is not a good idea. Why ? because it's raining boys !
Indeed, the rain of Isengard and therefore all the other ways to cnacel leaderships just turn this Central spell of the Dwarves into a total waste.
I like there is such a counter, however, it deprives a player from using a 5 powerpoint spell, which is quite incredible. I think balance could be better for these type of super spells if an alternative effect was implemented in case of a deprivation of leadership.
The description of this Central spell could therefore read "If this effect (4 time as much armor) is cancelled, a new effect applies nonetheless (+25 % armor to the troops caught in the radius of the spell)
25 % instead of 300 %. Cancelling leadership would still be a great counter but it would not turn into nothingness a spell that costs 5 pwp.
GALADRIEL, LADY OF LIGHT
The same applies to Galadriel in her bless form each time she uses an ability that normally, gives every allies nearby +20 % range, damage and speed. All the interest of that spell can be turn into nothing by activating Isengard's rain.
As there is more time to get benefice from it than the final stand of the Dwarves, it maybe less impactful. However, in this case also, I think that an alternative effect of only 10 % speed (or 20 % with the Ring), only half the bonus for speed without more damage neither range if leaderships are cancelled would improve the feeling and interest of such a spell.
It is also quite nonsensical that spells so powerful can be negated by a Nazgûl or by the rain. Galadriel is far more powerful in terms of the hope she inspires compared to the Nazgûl despairing aura.
Glorious Charge of Theoden seems to be not cancellable, and that is great, perfect as it is.