I scanned the first and last page of this thread, but if there's any details I've overlooked, feel free to point them out. Considering the approval, relative easiness, and the already long-wait for this, I am working on this right now. It should hopefully be done shortly and sent live sometime this week, assuming few to no interruptions. I do tend to get interrupted a lot lately.
For now, I'm building it so generals are provided a siege engines per army number and the marshals are provided siege engines per character/unit. This should allow both to have the relevant information without encouraging micromanagement.
Edit: Done. Should be live within the week. Marshals, vice-marshals, and sponsors should be able to see how many siege engines each noble in their army has, as well as the total siege engines in the army. Generals should be able to see the total siege engines in each army.
Oh, and those 'coming soon' offensive and defensive formations? They come extra with the siege engine numbers!