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Well... do you have the pattern for the joiner? (the piece of scrap it pressed out from is fine)

Cut the pattern in half on the line between the center wing ribs according to the plan. Place that over the mispositioned joiner and mark it.

How much of the joiner is outside of the marks?

If its a small amount (like about 1/16 inch) just trim the joiner to allow the wings to join up properly and don't worry about it.

If its a huge amount (like near 1/4 of the joiner area extending out) then you need to replace the joiner's strength for sure. (the surgery on the wing isn't as bad as you may think)

If its in between... can you get a picture posted?