The USB shielding appears to be just floating and not connected to anything at the PCB end of things.
That's your problem.
When I tested the original cables, ther doesn’t appear to be any connection between the original Tankstick connector USB /PS2 cables’ sheilding and any pin on the 9 pin PCB connector.
Sorry, I am going from PCB 9 pin connector to USB-A and Pin 9 on the PCB Header IS the shield for the Serial connector, and is connected to Pin 1 of the USB-A Male. (But there is no connection on the original to the USB-A end shield.)
I tried again using a pinout found on here, but still no dice, I only get power and no data and the data connections appear to be as expected and not reversed.
I haven't tried to test continuity on the Encoder Board though, there is always a remote chance one of the pins isn't connecting to the female connector. So that's next.
Then I am going to try going from the 4-pin PS2 connector straight through to USB (inactive) to see if that will work instead.
. (I am realizing now that the 4 pin PS/2 header on the X-Arcade encoder is an INPUT for programming the board directly from a PS/2 keyboard, that the 9-pin serial header is, I think, split off to USB-A and PS/2 PC mobo connectors.
Still I am now suffering pseudo-OCD to determine why my new connector isn't working.