Checksums will not help with this type of bug. Very likely the account to which the transaction was wrongly sent will also have passed the checksum.
If the address got corrupted on its way from GUI to server, then to network, checksum will prevent other nodes from accepting it.
Checksums are precisely the mechanism invented for unreliable transport.
It's unlikely that the address would have corrupted in such a way as to match the checksum, and this probability goes down exponentially with every added bit of checksum.