In case anyone stumbles upon this by Google like I did and is wondering if this CEC bypass works with the Mirabox Passthrough Nintendo Streaming Recording as well, it does. In this case it didn't appear that either pin was connected to anything on the board, so just a jumper worked fine.
It helps to have a https://www.amazon.com/gp/product/B09KRVJM8T?tag=hyperioforum-21 to test the connections after soldering.