They shouldn't twist. This type of tuner design is pretty much the standard for 'modern' tuners. The screw-down nuts should do 99% of the holding. So make sure they are tight, and not just loosely done up. When tight enough, the tuners shouldn't rotate even without the anti-rotation screw fitted.

I always fit the screws after I've tightened the nuts up, and drill the pilot holes in situ.

It may be that the headstock is too thin to allow the nuts to be done up fully, in which case you either need to thicken the headstock (can be done but a PITA), or cut down the length of the screw threads so that the nuts can be done up tightly (my choice). Stick the end couple of mm of the thread in a vice (the bit you are removing), and cut through with a hacksaw. 3 or 4 mm should do it, though double check by testing the length of thread needed to achieve a decent overlap first by removing a tuner and measuring against the side of the headstock.

Then smooth off the rough thread end with a file so that it

And maple isn't a soft wood. By far about the hardest wood normally used in guitar construction and you certainly need to drill decent pilot holes in it to prevent screw heads from stripping or breaking off.