Is it really this hard to set up such that lil stuff?
I used to take advantage of this glitch simply opening the app, then letting it on background while was loading game data > then changed my device's date/time > came back to the app and yes, I was able to get items available only in the past when I set backwards date, and also, things scheduled to be obtaineable on future, viceversa.
Now they fixed this, and the same trick explained above won't work, since they have set game to get time from the server where it is running.
But, GG's go to future option still works, and I can still shop items scheduled to be purchaseable in certain future dates.
The only thing I miss now is going back to past...and honestly it looks weird your explaination regarding being something technically this hard... It just need to kinda change the in-app internal clock...and this shouldn't involve GG's historical data stuff...does it?