Thanks for the suggestion.
Going by the simplicity the Maximo workflow has to be imported to Cinema 4D, I assume this simplicity should determine the level of complexity (or lack thereof) for the facial animation. I would exclude Joints here for this, as they would require a complete new weighting and creates a lot of considerations for the otherwise, as mentioned, simple Mixamo workflow.
I would think the most versatile technique would be the Pose Morph option.
I recorded a quick clip for you. This was done in just one minute. There are lots of options in the PoseMorph Tag.
In an older version this was explored here:
… as well in part two.
The Driver tool would be to name as well, here in conjunction with the Pose Morph
Does this come close to what you are after?