Engine shield and trans skid plate are 20 N·m (15 lb ft).
As for other under carriage bolts? Not sure which ones would be "normally" checked. If they are correctly tightened, and the use of a threadlocker (
IF REQUIRED FOR THAT BOLT/NUT) is correctly applied, they should not be losening up.
However, here is a list that might be helpful for some....
http://home.comcast.net/~f5fstop/H3_...GE_TORQUES.htm