Winow products have been pretty good but the FK-G30 seriously missed some QA testing. I got it for the same reason you mentioned, my current fork is 50mm offset and I wanted a little bit more as it could solve toe overlap issues. Problem is that they designed everything in the 50mm position, meaning when you flip the chip the rotor is now ~5mm off from the standard flat mount position.
Looking at the expensive forks (Columbus FutureCross, GT Grade Carbon Pro 55-70) they do the opposite, if you have the fork in the shorter offset position there are spacers for the flat mount calipers.
Looks like I have a few options - 1. Live with the pads making less contact with the rotor. 2. See if I can modify a standard flat mount bracket. 3. Buy a new fork.