Question:
Can I also create guidelines in a user-defined coordinate system?
Answer:
Entering guidelines into the user-defined coordinate system is currently not possible, and in most cases, it is not necessary. If, for instance, we take a roof plane (see Image 01), it is only necessary to enter the guidelines related to the work planes.
In the attached video, I have used the function "Guidelines → Bias by 2 Points" for the roof plane.