Sorry to hear about your deposit, the issue of deposit to the wrong network can actually be taken care of if the owner or anyone who has access to the finance/wallet systems on that platform are willing to handle it.
It is indeed a bit complicated and it can impact the security of their wallet/addresses to get private keys from certain address, so most casinos and exchanges usually refuse to do that with a reason that is a mistake by the user and they have stated about this in their T&C.
As far as I know, there are several casinos that ever given different policies regarding cases like this, deposits are processed with note if it happens again, they will not handle it anymore.
I suggest to contacting the owner or manager of the platform, because support will always answer no and we can't blame them either because they have to answer that way.

Regarding streamers from restricted territories, this actually happens in all casinos - almost all casinos have ever worked with streamers from the US or other countries that are on the list of prohibited countries from playing on their platforms.
The only ones who can warn them are the licensors - but I'm a bit pessimistic they/the licensors even care about that.