Not only do my passenger windows leak but i have problems with the boot/ rear window.

The lower half of the boots seal gets wet and sometimes i get water sitting in the recess between the seal and where its mounted. If you think of an 8 on its side, i get water in the valley.

Can you adjust the position of the lock so you can adjust how tight the boot lid sits against the seal?

i think the striker part can be adjusted , unclip the trim around the striker to check for available movement, also the side angled sections can be adjusted allowing the tailgate to close tighter

a quick spray of silicon cockpit shine on the seal may cure the problem without adjustment

I adjusted mine to shut tighter, it's a bit of a fiddle between shutting tightly and not having the tailgate open light on the dash. As well as the side angle stops being adjustable, there are adjustable bump stops at the corners of the tailgate, they just screw in or out to align the tailgate flush with surrounding body work. Be prepared for some trial and error.

Don't forget to mark the original position before moving the striker plate.