In your case (i.e. using blender curve objects) there is not much point in using the Z-Up tilt option, as that is meant for curves generated from other things. Since you’re using a curve object you can use the Z-Up Twist Method instead (it will give exactly the same results):
Since all the Z-Up Tilt option does is what the Z-Up Twist Method does, you have to correct vertical sections in the manual fashion (same as you had to do with Z-Up Twist Method):
i.e. correct, generally in increments of 90deg, for weird twists.
There is a python script that performs these “minimal tilts” for you but a geometry nodes version (I think) will only be available in Blender version 3.1 or up as (I think) you need an accumulator to implement a similar thing in geometry nodes.
Good luck.