Your comments

The latest IW lets you both correct bleeds and shift crop marks:
Please check our latest beta of the new IW Standalone, the feature is there:
Is it about hard/soft edges or that's modifying the geometry around edges? Any chance you can show an example of another software doing that?
Exactly, the next idea after making Origami standalone will be probably to add "a very tiny little editor" there :) At the end of the day, we'll end up with another Illustrator competitor... That's not in plans.

In case of standalone application, you'll need to re-export the fixed version of your dieline and reload it in Origami. We'll try to simplify that like we do with artwork in Boxshot, but it will still be a few extra steps.
I am not sure if Affinity Designer can have plugins at all, but anyway this seems to be quite a niche product so far. There's also Corel Draw, Sketch, InkScape and many other vector editors around. Supporting all of them may eat up too much resources, so at the moment I don't think it is worth it.

On the other hand, standalone version of Origami could be an option. All the editors seems capable of exporting SVG and we can load them to Origami for further processing. It will not be as simple as with Illustrator, but still an option for those who don't use AI.

No promises so far, though.
Please send us a sample PDF and before/after sketch. It seems that you can do that with shuffle, but I need to see the details.
May I see an example of those fold100/fold30 lines? Not sure how they work for you.