I honestly don't think it will go into the currency window, though. The currencies in the Currency Window are the currencies used to buy items from vendors. I could see possible issues with the phirius token item shop if they ever do put them into the currency tab. Would be better to just make them stack higher than 1k since there are items in there that cost 3k tokens which is 2 extra bag spaces used up if you're saving them to buy such an item.
I fail to see how they could run into possible issues putting them into a currency tab. Your argument is something may go wrong with the ptoken item shop... look at dias. They have always had a currency tab without issue, it would be simple to use similar coding which they already possess to place ptokens into a visual currency as well. The only thing stopping them is their want to do so.
However I do agree with you that they will not be placed in the currency tab, for what reason idk for sure, and the solution you posed would also be sufficient, for now...