The most recent discussion on motor temperature is in the middle of the thread Powering the stepper motors - #17 by mikromidas - posts 17 to 29 . It seems to be an issue that comes and goes. I have never found a problem with it, but my tests in that thread do suggest that there is not much headroom and so small variations can easily tip over between fine and too hot.
I have seen some pictures of builds with little heatsinks stuck on the motors (the kind that they sell as cooling kits for a Pi or something like that).
As a stepper motor the current is basically the same whether it is moving or not, unless it is actively released. Releasing the motors has not been seen to be necessary so far, and one would need to test whether it would alter stability. There were indications from testing positioning of the Block Stage that positional dither was worse on un-controlled axes.
Instructions for mounting the motor gears is an issue that we are addressing. The gear needs to be pushed fully onto the motor shaft, and then the screws need to be done up so that they sit fully within the gear. With standard screw head sizes that will fit. With the screws buried in this way there is plenty of clearance.
(from Assembly Instructions)
Also issue: https://gitlab.com/openflexure/openflexure-microscope/-/issues/302
and Forum thread: freshly-assembled-upright-microscope-v7-0-0-beta1 post 3