I am happy I could be of help. There is really nothing wrong with having the checksum flag switched off, but if you really want to do things right you will have write your own CS fixer in the programming language of your choice. The checksum is calculated in the following way:
You add up all the words starting from address hex $6000 until the end of the file ($FFFF), you store the word result (call it CS) at address $FFAE (so far this is what the checksum definition in the xdf file I published does, but this is not complete), and then at the next address $FFB0 you store the complement of CS to $FFFF, that is ($FFFF - CS). That's it. But note that the two words at $FFAE and $FFB0 have to add up to $FFFF in the first place, otherwise the procedure will not work.