This would help me nicely as a modder too. I often schedule events or duration-effects in strategic mode. For example, one event I have is that any champion who falls in battle between "event" and 40 turns forward has a chance to leave your service. But there's no timer or anything, so the player has to manually keep counting the turns.
Another is when a player finds a sworn dragon egg and becomes a dragonrider. Once the egg is hatched, the player must wait 150 turns before summoning the dragon (as it grows to maturity). Very difficult to keep track of!
If I may make a suggestion, it wouldn't hurt to have the ability as a modder to put stuff into your scheduler as well. I know it's not exactly what you wanted, but I wouldn't spam it or anything - just the most critical of critical things.
