How many PCBs did you have made before you built up a first article and tested it? If it's a small quantity and you are willing to make an adapter PCB, then you should be willing to make a new revision of the main board fixing the issues that require the adapter board.
Finish assembling one PCB with cuts and jumpers to make it work, note all (other) changes and then respin the board fixing all the mistakes.
If you are just looking for one working unit for yourself, you can stop here, but it sounds like you want to make a bunch of these.
Toss out the original remaining PCBs with the backwards pattern, and move on from there. Everyone that has ever laid out a PCB has gotten a package backwards at some point.