For argument's sake, are you saying I could change the project dimensions just slightly to 1792 x 832 (numbers divisible by 8) and it'll render with the PIP positions basically where they were?
Sorry that my first reply didn't contain enough detail. Some side issues have been raised that appeal to clarification.
1. Set your Project Dimensions to your desired output dimensions, they should be even numbers (refer to #5 and #6 below).
2. Open your Picture in Picture filter and adjust the display to your wishes.
3. Render without changing the Project Dimensions again.
4. When in doubt, refer to instruction #3.
5. 1792 x 828 should work fine for the AVC /MP4 render using the Magix Software AVC Encoders (Mainconcept or Sony AVC), because they are both Modulus 2.
6. If you will be rendering to a hardware encoder (NVENC, QSV, or AMD), do so at their exact output template dimensions, because nothing else will probably work.
7. I have tested these instructions, and assuming that you follow these steps in order, no further speculation should be necessary.
I don't honestly remember how I came to those dimensions. It's a compilation of different footage from various sources. I think I just assumed that since the render template was customizable that I'd generally be okay. This project kinda called me out of vid editing hiatus by surprise. Thank you guys so much for your time. Thank you mark-y. I'll give it a go.