I've switched a 30fps project to 24 in C4D, both in the proj. settings as well as the Render settings. When I import it to AE, AE only will see it as a 30fps source. Ok, so just manually change the interpolation to 24, right? But when I do that, it doesn't change the length of the C4D source. It simply ends when AE gets to the end of it's original length, effectively clipping the last part of the C4D file.
My workaround for now is to just leave C4D as 30fps, let AE bring it in at 30fps, and precomp the C4D layer in it's own 30fps precomp (in my 24fps main comp).