If proofs of payment are provided but in cryptocurrency, do you think the court will consider it even though transactions are tagged illegal with it? or will the case be thrown out and the owner of the property with the false claim of not receiving the money be allowed to go freely?
Although, it is NOT advisable to transact with crypto in a country where it is "illegal", the very nature of Blockchain (permissionless) allows anyone to access it at will. Laws/regulations can't be enforced on a decentralized network. Only on centralized exchanges and/or centralized wallet providers. What's stopping people from using crypto "under the radar"? Of course, expect to face fines or jail time if you're caught doing this. You'd need to decide whenever it's worth taking the risk or not.
I cannot tell whenever proof of payment on the Blockchain will be admissible in court or not. I'm not a lawyer, after all. My guess is that countries where crypto is "illegal", such thing will be outright rejected by the court. In countries where it is legal, this is still a regulatory "gray" area. It could or could not be admissible in court. With laws constantly changing, people would be better off using Fiat instead of crypto for day-to-day transactions. At least, that's what I think.