I do see a lot of merit in making changes to Lenght of War. But for me it would be far easier to be more specific if the UI was better. Right now I cannot be as specific as I would want about what I think is needed since I lack the experience with how the numbers change during a war to give a potential solution.I think the problem is deeper than just UI. Right now, a war will not end until one side is completely wrecked (depleting their manpower/money, losing significant amount of land), or both sides both reaching near wrecked state. In reality in a lot of wars, especially those over a particular region (can be big or small), when one side is clearly losing that region, they will start to negotiate peace to minimize loss, rather than let to war continue until complete victory/loss.
I think CK2's peace system is a bit too restrictive, since one can get nothing more than their wargoal in a war, but EU4's one is way too open, resulting in wars always seeking maximum gain rather than minimum loss. However, the problem is also half in the players, since that's the way most players playing the game.
And more restricting cbs could easily be part of the solution to the admittedly too open "wargoal". But again, I would need more experience with the exact number to suggest a well-founded solution.
Right now I am inclined towards a 0 to 100 scale for war enthusiasm changing according to more or less the same mechanics as now and with some thresholds for when certain kinds of deals may be on the table and at what price.