530 Nm is really just a marketing figure. It's what you'd get if both the motor and the engine (at it's optimal RPM range) was driving the wheels.
Realistically, that never happens due to how parallel hybrids work, specially when they're driving the same axle. On the H6 HEV specifically, that's more so a figure you get momentarily during launch control, which you need to activate by turning off VSC.
Power Split systems are usually designed to distribute power as equally as possible throughout the engine's RPM range. You can see from the dyno chart above that the motor + turbo keep nearly consistently high torque up until the 5000 RPM range, when the raw power output of the engine takes over.
We would've likely seen a larger output on the chart if the rear wheels were also getting power, but that's generally been a criticism of the H6 HEV's FWD DHT transmission.