New update!
The genuine harness finally arrived. I picked it up yesterday and oh boy - what a difference compared to the AliExpress one. The genuine harness is super rigid, has all the necessary clips to properly mount to the bumper and is covered in plastic tubing compared to just electrical tape. The connectors have an extra "lock" that slides in (similar to other VW connectors) and I'm very happy with it.
Today I had some free time so I (for the 50th time) took out the bumper and started taking apart things.
My initial goal was to leave the genuine 10-pin harness intact, and connecting the two wires from the license plate lights connector to a 10-pin male connector so everything will work like it came from factory. However, I wasn't sure if the two wires use the exact same pin as the parking sensors wires and that also requires purchasing this male 10-pin connector which would delay the whole process. So instead, I opted for
@Cuzoe's suggestion to disassemble the AliExpress 8-pin harness and use it with the genuine 10-pin harness to re-pin, while leaving out the two wires that are for the (original) license plate lights.
Before I started working on the wires, I figured I'd use the fact that I took out the bumper to increase the PLA holes from 18mm to 27mm. This is in order to accomodate the genuine brackets, which are not "flat" but angled towards the curb (I posted a proof on some other page before). The PLA brackets, similar to the front PLA bracktes, have a "lip" that has to be painted. My sensors and brackets are yet to be painted, however you can take a look at how it looks now after increasing. Note that it does not sit flush since I have leftover glue residue from the old bracket,.
Fortunately, I had a genuine VAG pinning tool that was a perfect match for these type of connectors which made this task very easy - the pins came out like butter from both connectors.
Next, I had to figure out which pins to insert the 8 (out of 10) wires from the genuine harness to the 8-pin connector. In the previous page, I documented a table of the pinouts for the 10-pin connector, however I could not find a wiring diagram for the 8-pin connector, so I figured since pin 1 & 2 on the 10-pin connector are used for the license plate, I should just deduct subtract 2 from each pin number (so for example, pin 10 on the 10-pin connector goes to pin 8 on the 8-pin connector, pin 5 to 3 and so on). While doing that, I verified the wire colors on the 10-pin connector diagram I posted on the previous page and the colors indeed matched. I wrapped everything in cloth tape (while taping those two extra wires for the license plate lights) and attached the plastic angle holder that came with the 10-pin connector - fit like a glove!
However, after everything was connected, the parking sensors still failed to work, even after resetting the DTC on VCDS. I assume this is obviously because my re-pinning process was based on a guess and not on the actual pinouts for the 8-pin connector.
@Cuzoe or
@IWMTom if you have any idea where I could get this, let me know.
I don't mind buying an hour pass to erWIN again, however using my VIN it only gave me the 10-pin connector diagram...