Did you try it and get the anti-cheat message? (I'm not actually sure what the message is lol). You should still be able to fight them in water currents, as they can still 'path' to you, even if they don't ever actually reach you.
Actually, I didn't get any messages, but unless 36 tokens is the base for enraged zombies at diff(7), I think something may be wrong with my platform.. xD
Collateral damage is the only likely culprit and the area in question is a 2x2 area with 1 meter of standing water to negate the fall damage and to protect the hoppers beneath the water to collect the drops that kept getting destroyed by errant creepers when the water wasn't present..
Yes, the base is around there. Dif 7 doesn't give much more than dif 5. So your reward sounds about right.
You can continue to get normal things without fighting in the open. If you want tokens, you need to ensure that the monster has the ability to come at you. One way to "control" the monsters would be to use darkrooms and have them stand in water to move to you. You could then hide out in a room with hoopers and kill mobs. This creates an area that is hopefully safe to attack in without the risks of running around in true open combat.
Oh pffffft I totally didn't forget to check the tracker to see if my issue was already known about.......