If you are unable to make offers, make sure the signing wallet has approved WETH spending by the X2Y2: Exchange contract. You can check ERC20 approvals on Etherscan.
If you are unable to list items, make sure the signing wallet has approved the collection's transfer by the X2Y2: ERC 721 Delegate contract. You can also check this on Etherscan by selecting the ERC721 tab.
To troubleshoot other methods, store the TransactionResponse that is returned. Then use TransactionResponse.wait to get a TransactionReceipt which contains the transaction hash. You can then manually find this transaction and see what went wrong.
For all other issues not covered here or in the error codes above, get help or submit a bug report at our Developer Hub.