Not sure if this is intended, but in my inventory and when in ghost form, the combinator maintains the graphic you've set (i.e. the diode model). As soon as it's actually built, while works fine, the graphic immediately switches to look indistinguishable from the Arithmetic Combinator.
See pic following, the one on the left is ghosted, the one on the right was just built and you can see now looks like Arithmetic Combinator.
https://imgur.com/a/EVIINWO
Thanks for the good work on the mod.