It's not that they are fake persay.  I have seen
(probably) the same cels that you are speaking of.
 I'm pretty sure they are studio or at least
professional reproduction cels.  So, they are cels
of the show but yes, the series is actually CG. 
So, in order to get actual production work from
it, you would need to hunt down
sketches/genga/douga/etc.