Water leak from hatchback door

When I worked at the dealer we would trouble shoot water leaks with a garden hose. You'll need a helper. Get in the hatch with a flashlight. Have the helper spray the garden hose. It's important to start at the lowest possible point. Spray for a while while you look and listen for leaks. Then move up a little with the hose and continue.

I'd pull all the plastic grommets out first so you can see quicker when the water starts to leak inside.

If you start from the top water will run all over and you'd have no idea where the leak is actually coming from.

Dry it all up, take the garden hose and run it at a light flow over the window molding for five mins.
Check if you got a leak inside
No leaks , do the same with the spoiler.