It doesn't matter if you buy energy from the modded version and change to the legit version JC can see that you already used modded version
This is also not the reason I'm asking. I'm not trying to dodge JC, I already know what will get me flagged and banned (having over 600 energy, participating in Full Marks, reporting bugs, etc.)
The reason why I'm asking is because I only use the vanilla client on my phone. As much as I trust OP and I'm super appreciative of their work, I'd prefer not to load modded .apk files onto my very expensive smartphone in case something goes wrong. I only use the modded .apk in a safe, controlled environment using Bluestacks on my PC. When I'm away from my computer, like at work, I play vanilla on my phone. What I used to be able to do was use the gem cheats to buy a bunch of energy in the store before leaving my house so I could make some solid progress using the vanilla client during my downtime at work. Now, it seems like this cheat doesn't work on the store anymore.
If you really want to stockpile energy, it's best to make sure that you don't go over 600 (unless you have spent real money on the game before) otherwise your account can get flagged, regardless if you are cheating or not.
While it isn't as convenient as the store, JC tend to run a lot more brilliant bargains these days which should allow you to buy energy from those.
Brilliant Bargains cost IRL money though, don't they? One of the key reasons why we have this mod in the first place is to skip the scummy microtransaction process and play the game how we want to play it. Plus, Rowling outed herself as a horrible person and I'm not giving her a single penny ever again. She owns the IP, so she gets a huge cut of the microtransaction revenue from this game.