As many others do, I have a ongoing agreement with 2 friends in my guild to buff a series of buildings for each other, to maximize the effect of the buffs we produce - in our case, we buff each others gold coin production chain, with Basket buffs, providing 9 hour boosts.
Initially we intended to set up a schedule where player 1 buffed all 3 at a set time, then player 2 did the same 9 hours later etc, but this only worked out for a very short time. Real life has a nasty tendency to get in the way and mess with our setup, not to mention connection problems and the occasional "wops, I forgot, buffed you an hour late".
The only way we found to counter this, is to message each other after every time we buffed, adding the time of the the buffing and the expected time of the expiration. But we are old and forget things, and every single day there is one or more slight cockups in this and all of a sudden nobody knows when a buff will actually expire.
Seeing as the time of the buff expiring is already within the game, why not make it possible to see how long it has left by clicking a building that is currently under the effect? Simply adding a countdown timer, not necessarily 100% exactly at the second but at least showing how many minutes it is left before the buff expires, would help me and I guess quite a lot of other players out, and would be seen as a small but very helpful addition to the game.