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.
Not from the GUI to server, but during the interpretation in a corrupted Java process. The Java process simply can do any crazy thing when crashing. It's why many of You get their blockchain corrupted time to time - exactly for the same reason - Java process got corrupted during blockchain update. But in our case Java process got corrupted (for any reason) during transaction.