How do G2/G3 interact with a rotated coordiante system via G10 L2 R-?

As per the title, I'm wondering how a tool head will move when the active coordiante system is rotated via G10 L2 R- and a G2/G3 command is issued. Specifically because the docs say "The axis of the circle or helix must be parallel to the X, Y, or Z axis of the machine coordinate system." 

Case active plane = XY: this would seem to be the easieast to handle, but just to check, are I and J rotated to represent deviations in the rotated coordinate system or no?

Case active plane includes Z: this is trickier, because both options present apparent trouble. If the arc's axis is in the macine plane, say XZ, it seems to be impossible to use G2/3 in such a plane with a rotated coordinate system as the post-processor can't account for it and the tool would take a path different than desired. On the other hand, having the arc be in the X'Z plane (rotated), respects the path desired by the postprocessor but seems to be in contradiction with the docs.

I don't have a LinuxCNC machine installed so I can't do the practical experiment myself (I'm actually about to build a machine and I'm trying to understand the pros/cons of each system). Thanks in advance!

Ok, I think I answered my own question. I spun up a quick VM and ran linuxCNC within it. Indeed, the arc motion commands G2/G3 accompany the rotation of the coordinate system. That is, if you perform

G10 L2 P2 R45
G55
G2 X2 R1 or G2 X2 I1 -> this creates an arc rotated 45deg so that it starts at machine 0,0 and ends at machine 1.414, 1.414

If you instead do
G18
G3 Z-2 K-1 -> this creates an arc from 0,0 to 0,-2 that is contained in X'Z, where X' is at 45deg wrt both X and Y.

Maybe I misunderstood the docs, but this is the situation that makes most sense to me.