"Ju88 prop-pitch in CEM. My understanding is physical lever forward, on-screen slider goes up, pitch is increased = greater load on motor, revs drop. Lever back, load decreased, revs rise."

That principle of operation is correct in theory - Now, I haven't flown the JU88 in the game, or even messed around with CEM, however I've flown a few AC with variable pitch props. All the AC with VP that I have flown had a constant speed unit (CSU) - as I think most German engines of the period had (as opposed to the early spits 'take off' and 'cruise' settings).

With a CSU, you use the prop pitch lever to set your desired RPM - hence moving the lever forward would increase RPM and Vica Versa. The constant speed governor mechanism (which in JU88 props would probably have been centrifugal force operated weights), then automatically changes the pitch of the prop blades to maintain the set RPM depending on what you do with the throttle.

For example if you set 2400 with the prop pitch lever at a given throttle setting (lets say 50%), and then advance the throttle to full allowing more fuel/air mixture to be burnt, RPM will initially rise, centrifugal force will act upon the weights in the CSU, coarsening the pitch of the blades which then take a bigger 'bite' out the air, thus putting a greater load on the engine and slowing it back down to the desired 2400 RPM, but maintining the power change becuase of the greater volume of air flowing through the prop.

Make sense? Hope that explanation answers the question!

On the other hand, if it didn't have a CSU, then just think of the pitch lever as an RPM lever! Push it forward rev up, pull it back rev down. Remember "throttle up, rev down, throttle down, rev up", else you'll blow up the engine!