They're only buyable with muh coins now, and since muh coins are transferable to cash points, the backwards should also be possible in my opinion. But that's probably a harder or a lower priority thing to implement, so I propose adding HE versions of bubblegum/battle manual to the cash shop for perhaps a higher cost, like 2500 premium coins instead of 200 muh coins, this way the "exclusivity" problem is solved, but the incentive would still be there to buy them with muh coins.
