Propeller bolt torque

All Rotax bolt patterns that use 8 mm bolts to mount the prop to the gear box flange should be tightened to 175 inch pounds. All Standard, HP and HPL hubs that use 3/8" bolts to clamp the blades or mount the prop should be tightened to 35 foot pounds.

SO the manual is totally wrong?

I can see how this is a little confusing and happy you posed the question! You are reading the manual incorrectly. The 315 NM (232 ft, lb) Is the max TQ the propeller shaft can be subjected too, not the TQ spec for the bolt to attach the propeller.  The propeller manufacturer sets out the Torque limitations for the attachment bolts. 

Example:

In the case of a Warp Drive propeller, the bolt TQ is:

AN4-20A Clamp bolts - 120 in/lbs, 10 ft/lbs 

8mmx75mm or 8mmx90mm Mount bolts - 175 in/lbs, 14-15 ft/lbs 

https://avsport.org/acft/WarpDrive/Prop_Manual.pdf