Wikipedia (yes I knoiw) says X30XE compression ratio is 10.0 to 10.8. Atmospheric pressure is 14.7psi. Therefore, at low RPM (such as when cranking), the maximum cylinder pressure should be between 147 psi and 158.76 psi. X32XE is listed as 10:1, so 147psi.
Given the accuracy of most cylinder pressure gauges (my Gunson one is carp) anything from 140-160 psi would seem 'normal'. Of your readings, only Cyl#1 looks Ok to me. The fact you've got some above normal, and some below normal suggests to me it isn't valve timing. 190 psi in Cyl#6 makes no sense to me.
One thing you can do is buy a cheap borescope/endoscope off eBay. Shove it down the spark plug hole and take a look at the piston crowns and if possible valve faces. If one or more pistons are cleaner than the rest, then this is a sure sign of water in the bores steam cleaning them. They'll probably be black (covered in carbon), but if they're coked up good and proper then you're getting oil in the bores which is either piston rings or valve stem seals
Chucking loads of oil in can change the compression ratio if any ands up sitting in recesses in the piston crown. This will raise the compression ratio. The purpose of the oil is to help seal the piston rings on a dry/cold engine and as such you only need enough to get down the sides of the pistons in the bores to wet things. If you're doing it on a warm engine, then oil shouldn't be required because the bores and rings will still be wet (hopefully!) from normal running.
Your predicted pressure would be correct but for 2 factors:
As the air in the cylinder is compressed, heat is generated. This further increases the compression pressure. It won't be completely adiabatic due to heat loss to the cylinder walls, and it will depend greatly on engine temperature and cranking speed.
Valve timing is offset relative to TDC/BDC, so for some of the compression stroke, the intake valve is still open. at cranking speed, this is enough to effectively reduce the length of the stroke.
It matters not. The variation between cylinders is what is significant, and I think this engine is not in the best of health.
Given the lowish mileage, I'd guess it might have had a cam belt failure and be suffering from bent valves, or piston rings having been crimped into their grooves by impact with the valves.
I too suspect that compression would be low across the board (or at least on one bank) if the cams were timed incorrectly.