The problem with using diamonds for those functions is that the calculations for determining the cost is broken. Taking an hour off the time remaining can result in a HIGHER cost in diamonds…kinda the opposite of what should happen. Also, you’re gonna end up wasting a load of diamonds using them to speed up troops. 5 minutes and 55 minutes both cost 60 diamonds. 61 minutes and 119 minutes both cost 120 diamonds. Beyond 12 hours, you’ll find that the cost will randomly go up and down as the time remaining decreases.
I would suggest that PG simply reverse the timer reduction, but since they have already shown they dont give a duck about player happiness, they need to fix the calculations. Set an exact time to diamond cost, like 1 diamond=1 minute, instead of whatever broken system they currently have in place.