Seems like projection wasnt done at the lower level for circles/ellipses.
However I am not quite sure if this was supposed to be happening at a higher level?
Just a little unsure because I found this comment for arcs:

1. curve is None means arc is called from bulge conversion
2. nothing should be projected at this stage, since the
3. lwpolyline (the only entity with bulges) will be projected
4. as a whole afterwards (small little error; took ages to debug)

Not sure if @Lukas Treyer (cnd) is still maintaining this addon?
if not, maybe @Campbell Barton (campbellbarton) could check?

@Bastien Montagne (mont29): do you know about this addon?

Eeeh, no, never worked on that even… I’d say try to poke @Campbell Barton (campbellbarton) again, maybe? Otherwise, just commit, you'll get reports soon enough if you break something ;)

@Campbell Barton (campbellbarton) : do you think this is fine to commit?