I've just looked at a few pictures of the Catalina, so if no one else is willing to have a go, I will.
I agree that the line of thrust is above the line of drag, producing a nose-down moment.
I agree that the centre of gravity of a tricycle gear must be ahead of the main wheels.
I don't agree that the centre of pressure is behind or nearly co-located with the CofG. To begin with, the main wheels are quite far back, and I believe they are for ground handling only, so the CofG could be only barely forward of them. The mains, from the not-very-good picture I have, appear to be about 2/3 of the way from the leading to trailing edge of the wing. Normally the CofP is about 1/3 of the chord back from the leading edge, but considering the shape of the Catalina, the hull would contribute significantly to the lift, moving the centre of pressure forward from there.
Any portion of the Thrust/Drag moment that the difference in CofG and CofP does not balance must be provided by the tail down force of the horizontal stabilizer.
Does that sound plausible to you?