i'm curious why it's the MK5 Jetta door that matches, not mk6?
I've seen some crazy things over the years, I couldn't tell you the exact reasoning at the factory for it. The Golf and the Jetta were on the same platform until the MK6 Jetta, but the SportWagon did not go to the MK6 Jetta body. Look at a 2012 JSW and a 2012 Jetta sedan...........different cars. The Jetta Sportwagon continued on with the MK5 Golf platform, since the MK6 Golf was just a minor facelift the hood on the GTI didn't change and so the MK6 Golf and the JSW share the hood, but the doors were redesigned on the MK6 Golf/GTI. Most likely a side collision update, plus the MK5 door design was an odd 2 piece design that was glued and riveted together, the MK6 was a more traditional shell with the outer skin flange edged to the inner. Might have been a streamlined supplier and factory floor assembly update thing, either way the JSW didn't get it, probably because they knew they were going to update it to the new platform in a couple years.
Long, boring story short, Bob's your uncle.......MK6 Golf hood, MK5 Jetta door.