I develop ProBuilder and the rest of those tools (ProGrids, Decals, etc). I also work on a visual programming language called vuo.
As it seems it crashes somewhere deep inside Apples QuickTime kit (QTKit, where "QT" means QuickTime here, not "Qt"). Apparently others also had issues with QTKit on macOS 10.14, e.g. https://vuo.org/node/2394: "The underlying problem is that, starting in macOS 10.14.4, a video library that Vuo uses (Apple’s QTKit) is broken. Other apps that use QTKit have also stopped working."
I have a lot of experience using Motion to create FCP X templates, and awhile ago I spent a bit of time trying to make this work, and I wasn't able to succeed - for one thing, as far as I can tell the audio from the FCP timeline cannot be passed to the Motion template at all. I also attempted to create a workflow where the user could export audio that occurs for the duration of the effect as applied in FCP as an audio file replacing the audio placeholder in the template - but that didn't work either. I actually found that even while still in Motion it was sometimes difficult to get the comp to correctly recognize when the audio had been changed out... I was able to implement such a workflow by creating an FxPlug effect to offer a file selection window in FCP for choosing the exported audio, doing the audio analysis and mapping to visual parameters etc. I built the FxPlug with Quartz Composer (and FxFactory) and used that FxPlug in Motion to make the templates... It worked, but for other reasons wasn't as useful as I had hoped... I plan to try to do it again sometime soon using Vuo to create the FxPlug [ vuo.org ] [ https://vuo.org/node/2442 ] - I have partially built it and it looks promising but have been busy with other projects and haven't finished it yet... Sorry to be offering discouraging news, but maybe you'll have better luck than I did.... good luck : )
Yes, best to use Kineme3D or the v002 Model Loader plugins to do that, but out of the box you can also use the Mesh Importer which supports .dae file.
Check out Vuo too, it is far more smarter with 3D objects: https://vuo.org