Three problems with strokes.
Here is a sample file.
sample.afdesign
Stroke to a curve with pressure.
1. Stroke is rendered with some kind of jitter. This happens very often to strokes with pressure.
2. If you apply Layer > Expand Stroke, round edges get sharp points. This happens even without pressure.
3. Again, Layer > Expand Stroke is very inaccurate.
Blue: Original
Red: Expanded stroke
While an offset of a bezier curve cannot always be exactly converted to another bezier curve, Affinity Designer's accuracy is very poor compared to Adobe Illustrator's.
