Yeah, I was hoping the visual marking of new roundabouts would be easy to pick out of the source code, but last time I looked into this it didn't seem to be at all obvious. Having said that, I've learned a bit more about how WME goes about its business since then, so perhaps I was overlooking something that time...
True, it won't work for messed up roundabouts, but I think the main use for this option would be to make it easier to correctly name (or not-name) a newly forged roundabout, to prevent it from ending up an annoying red blotch on the map.
HTC One X - Android 4.1.1 - Waze 22.214.171.124 - International Server
AM for NW London and the M4-A404-M40 loop - Editing Expert
WME enhancement scripts (WMEOD:URO:LMUR:SRS) @ userscripts.org