I think I can, though it's not simple, and there is, of course, still no guarantee that it won't suffer from some of the same problems as the others. Note that all of this, while I have written (at least parts of) it down before, is still highly speculative and if it were to happen, it wouldn't be in the immediate future.
Seems complicated, I'm not sure I grasp it correctly. I'd have to re-read later.
Not sure how I feel about war fatigue. Sounds weaponizable. "We won't actually fight them, but we'll use this war fatigue as attrition to help our other allies, closer to them, do the actual fighting against the penalized realm, while we'll focus on courtier work back home".
I seem to recall having had an idea relating to recruitment centers as well, back when it was decided to just scrap it all. I don't recall what it was. Maybe if recruitment centers got less costly, or gave better results, when built by realms that have lots of battles (victories or defeats, regardless)? That way even the losing realms get the boon. And realms that are often at war can gradually invest to have better centers overall than their more peaceful neighbors.
You'd have to factor in realm size in the bonus, though. Some realms can easily have lots of small battles without really being at war. At least, against rogues. Maybe just not consider battles with 3500 CS or less of rogues. Feels to me like huge battles with the rogues ought to count, but not the regular every day skirmishes with random little rogue units.
Perhaps give a higher bonus when the battle happens in your own realm's regions. Or based on distance from the capital. Just to make sure the mechanic doesn't make lopsided battles moreso.
Does feel to me like more militaristic realms should have better soldiers, but it often isn't the case, because the more militaristic realms must spend more on their mobile armies and thus have less funds to invest in better RCs, thus they just take whatever they first get.
