Hi rom, thanks for posting the file.

You're probably not getting the original vertex normals coming through for the rendering. Check if you've accidentally disabled it in import options or if you're doing some kind of editing operation that is discarding them.

Here's what I get using just defaults:

Export out of MoI looks like this (complete default settings, nothing adjusted):



Import into Cinema4D looks like this:



Render in Cinema4D looks like this:



Render in Blender looks like this:



re:
> but it'd look bad in any render engine

No, as demonstrated above it should look fine in any render engine just as long as the good vertex normals are getting used.

- Michael