No, it is not ok to cheat and the punishment for doing so is expulsion from the game and deletion of the account with no chance to get it back. If Bytro has not done anything maybe it is because they are not multi-accounts, or maybe it is that they have not reviewed the case, do your best to report through the game and wait one more day to see.
In the meantime I suggest you to place spies in intelligence mission in the countries that you suspect that they are multi-accounts, to see if they manage to intercept the communications, if there is communication between those countries through the game chat then they are not multi-accounts. On the other hand I also suggest that you contact the other players who are not your allies and explain the situation to them, suggest them to create an alliance between all of them to join forces and be able to face the multi-account, tell them that only by joining forces they will be able to defeat it.
See, the thing is that two of the three accounts have the exact same name, with the same numbers in different spots in the name. Not only that, but the three countries are now freely trading all but one of their provinces to the main country, while using their armies to conquer other provinces from other countries. I'm sure they're trading all of their resources as well. While myself and one of the other remaining players in the game have noticed and are trying our best to counter this player, the majority have either gone AI, aren't answering, or don't care. Another day, another active player swallowed up by this cheating player. The evidence is staggering, and the person accused has been accused in the newspaper, and didn't even care to deny it. He knows he is getting away with it, at least for this game. It's really a bummer that it is taking so long.