Reassembly: unsure of torque requirements for compressing cells together after installing new cells.

Tight

 

The clamp assembly for the modules has black crossbar tubes that control how much the modules are compressed. The bolts you're talking about thread into these tubes. Just tighten the bolts until the tubes are bottomed out on the white side plates and the bolts stop turning. There's nothing to worry about. The bar length in the Gen 2 battery is exactly what's needed for 28 modules.

 

Torque values likely shown in this. Not seeing it, can dig more. The Repair Manual doesn't seem to get into breaking down the pack into individual modules, so maybe they don't mention. Odd though.

 

I guess if we really need to use a specific value. Try 22 ft-lb.
The bolt is an 8mm with 1.25 thread pitch. Type 8T. Toyota spec is 22 ft-lb per the Service Specification section of the repair manual.
Now that we know a number, we can all sleep better tonight.