Affinity Design can ALSO Trace/Draw Vectors, in Designer Persona, on or near Pixel objects of a PNG image, so more study is needed.
Then export to (true vector) SVG...and skip the 3rd party AutoTrace program.
Then import the new SVG into MoI...

https://www.youtube.com/watch?v=7N-ePdWaBns
The video goes so fast, and so low volume, that it is hard to follow...

AD vector tools:
https://www.youtube.com/watch?v=hsbtJxqBi_I

- Brian

So, using Affinity Designer, I am shifting focus to reproducing 2D curves in PNG pixel image, with Vectors, using the numerous AD vector Tools.
Include scaling/alignment references. Save as AD (true vector) SVG, to be imported into MoI. This bypasses using Image command in MoI.