I think the effect of an out of time hpfp would be lower than expected fuel pressure, and I believe the adjustment would need to be in the fuel trims. The car would still set fuel injection and spark at the optimum crank position, it just wouldn’t have the expected fuel pressure resulting in less fuel than expected in the cylinder. The o2 sensors would then tell the ecm more fuel is needed, and the car would adjust the pulse-width on the fuel injection to give more fuel - which would show up as positive fuel trim. But you’re not showing any fuel trims to speak of.
As for checking the timing, I think the only timing marks are on the timing chain itself and the sprockets on the crank and fuel pump cam, not on the cam followers. The manual calls for use of a special tool to check the pump timing - basically lock up the crank shaft in a particular position using one special tool, then insert the second special tool in a hole and it tells you if the cam is timed properly or not.
There also seems to be a section in the manual for adjusting the pump timing. Very little info and I can’t really understand what they’re telling you to do. Not sure this copy of the manual I have is complete.
Finally - here is someone’s thread on replacing the tensioner on the aux chain without pulling the motor.
https://www.landroverworld.org/threads/auxiliary-chain-and-sprocket-change.44405/page-3. Doesn’t look fun. Hopefully
@theegovernor will give you some better guidance on how to retime and maybe replace the tensioner if it has gone bad.