Hi Dr. Sassi,
Thank you for the detailed response. I did end up figuring out a work around to my issue. First I reset the bind pose of my character into a T pose as you advised and from there I retargeted the mocap rig in the master controller settings of the character object. This gave me much more accurate results of movement and joint rotation, and I no longer have my characters' fingers crossing over.
I also went through working on testing different retargeting approaches in new scene files as not to contaminate the original project. It is interesting how certain movements can render model designs basically useless as you detailed above. I guess that's part of the process of figuring things out, trial and error like always!
Anyways, I'll let you back to your work. Thank you for the help and I'll take it from here