Read some stories on adding xtra insulation in ceiling. How it adds mass which may result in house maintaining elevated temps at night due to thermal transfer. 2-3k lbs of insulations has lots of stored heat and radiates into house during cooler night. Fix is to add low mass insulation, aka foam.

It's a minimal amount of information but usually expect airsealing the ceiling to have the biggest return on investment for energy and comfort in most existing homes.

Air sealing an attic GBA.

Air sealing attic FHB video

In existing and new construction airtightness as measured by blower door testing is a more important performance metric than insulation or R-value.

House is built in L shape. West section has no attic access. No hatches, no closets, nothing. How do I even get up there? Roof is 4/12 pitch, 24' wide so vertical height is 4' approx at peak. Bedroom section of house has same roof profile. It has 2x6 trusses with no vertical supports. U could fly drone down middle. I assume west end is built the same. The thermo foam panels with ridge vent seems like a good idea. If I could somehow get up there.

Can't you do the ridge vent from outside? You'll need to remove the shingles at the peak and maybe another row to install the roof vent, but replacing those shingles is a no brainer.

For a northern heating zone R19 ceilings and R11 walls seems pretty light. I'm in CA which doesn't get near as cold (or hot) and the minimum code allows is (IIRC) R35 ceiling /R19 walls.