Question regarding a 2008 Touran, 1.4 TSI BMY, won't start, error code P2293

Hello,
I have a 2008 Touran with a 1.4 TSI BMY engine, with approximately 225,000 km on the odometer.
The engine is turning, but it's not starting. Error: P22893 - Fuel Pressure Regulator 2 - Missing Power.

High pressure build-up via OBD at 7-12 Bar in the rail during starting attempts. A minimum pressure of 40 Bar is known. Engine sporadically starts when starting, but doesn't really run.

My first idea was whether the high-pressure pump was faulty. I have exchanged, no change/improvement. (The shift lever is okay according to mileage, easy to operate, the camshaft has no visible signs of wear regarding tracks etc.)

Compression measured: Cylinder 2-4 ~9 Bar (cold engine), Cylinder 1: 15 bar. Fuel puddle in cylinder 1. Continuous Injector.
All injectors replaced. Still the same image, pressure still at 7 bar. But the pressure is now being held in the Rail.

Tax times: So far, the inlet camshaft seems to be in the correct position for OT, but the outlet camshaft is not in the correct position. That would be my next idea, but it doesn't directly relate to not reaching the minimum pressure, does it?

Does the system pressure always increase cyclically only shortly before the injection stroke, or must it be permanently present?