Is there any rule against creating another account in this situation, or could it lead to additional penalties?
It's not allowed, the rules simply say not to do it, but there are several posts from the admin where it says that doing so could result in a ban.
Don’t try to circumvent any indexing restrictions
https://itch.io/docs/creators/getting-indexed
and:
Keep in mind creating a new account to circumvent any restrictions or ban evade will result in permanent suspension from our platform.
“I have read the rules you sent me, thank you for the information. But I guess I’m just unlucky. I already replied to the email I received 7 days ago, but I first had to wait 7 months for them to respond to my email about why my games were not being indexed. And now I will have to wait again without knowing how long it will take for them to tell me whether there is a solution or if it is permanent. This situation is very discouraging, not knowing how long I will have to wait for another response. Well, it’s really disappointing, but thank you for your time; it was very helpful.”
