Officially they are not legal for UCI regulated events, but usually nobody cares if you're not racing at a national level.
I'd include that above statement at State level too here in Oz. The comms go right through the rules and bikes via a jig to make sure saddle and extensions are within the limits and check the bike out as a whole.....not sure how I'd go trying to 'sneak' the disc covers past them but.
I also got a wheelbuilder cover made up for my specific wheel and they got the dishing wrong so the cover bubbles out in places. VERY ANNOYING!!! Especially since they had all the information of the wheel AND they never responded to my emails
. I ended up drilling small holes right near the cassette and mini zip tying the cover to the spokes for a smoother surface. Apart from that the only other option I have is cutting the cover and faning it out more to match the dish but then I would have to infill the space and then the tab holes would not match up so it's staying the way it is. Almost a complete waste of $85 bucks.