Something I’ve also been meaning to mention for ages. When deleting nodes on a curve, Glyphs tries to preserve the shape of the existing curve. But if deleting more than one node (on different curves), this doesn’t happen:
the algorithm that tries to recaluclat the shape can explode if you delete some nodes in a row and back when I looked at that the last time, I didn’t figure it out. I need to have another look at it to see if I can improve that, now.