That would be great, thanks for your attention. However, and that just my 2 cts, maybe the improvement of Part_Loft behavior could be more useful than using Part_Sweep? In this way you wouldn't need to modify your taper angle feature and Loft feature would be improved generally speaking. I have no idea how difficult it would be. It's up to you of course, you're the dev. and you've got the skills. I hope you'll find a way to success
Such trace back system would so powerful to select features, I hope you could success too.It's kind of complicated. Because topo naming trace back is ambiguous by nature. I'll probably add a similar command to 'Pick geometry' to offer selection of trace back.
Offtopic: have a good presentation at FOSDEM tomorrow: https://fosdem.org/2021/schedule/event/freecad/