The VR-1 thinned out for the low mileage. I guess the boxer engine is harder on oil than others.
Your lowered flashpoint indicates some fuel dilution. Fuel dilution will affect any oil, regardless of what brand it is.
The KV100 9.49 is within the SAE J300 definition for new oil of a 10w30 (9.3 to 12.5 is the range for new "30" oil). That's a normal viscosity swing engineers know about and design for.
I think your choice of oil is good, although a change to higher-performance Euro spec oils might help a little, as in M1 or Castrol 0w40, basically anything with the MB 229.5, Porsche A40 standards.
This isn’t about dynamic viscosity, it’s purely a matter of kinematic viscosity; getting the oil pressure high enough to push it up to and through things like turbo bearings.
Sounds like you have no understanding of dynamic vs. kinematic viscosity. Nice try though.