Gems of War on a 9.7" iPad Pro with iOS version 12.2.
For a variety of functions, the state shown on the screen does not change until I leave the immediate display and then return.
Defeating a level in pet rescue does not show the next level as available to play – and it can’t be selected – until switching to some other tab (rewards or whatever) and then returning.
Defeating a champion in the Class Trial not only fails to show that champion as defeated but will allow me to select them for battle a second time. (Gives an error message of “class event double complete 0” if I actually try to fight them again.)
This problem is also seen for things such as task contributions and troop trait updates.
So from experience, I can tell you that if you tried to purchase Tier II again, it would say that you’ve already purchased it and prevent you from doing so.
I think this applies to basically all the aforementioned scenarios, except for being able to repeat the 8th Pet Battle indefinitely (within the time limit). You don’t get any bonus rewards for doing so, anyway. It’s sometimes possible to repeatedly click ‘Collect’ on the Rewards, but it doesn’t do anything.
There’s one situation where it can hurt you quite a bit, when you go brain afk in the Bounty event and keep repeating the same low score battle until you get a strong enough déjà-vu feeling. In my defense, the Bounty event seems to be designed specifically to make me go brain afk.