I wonder if it would be possible to implement a feature that makes it possible to attach an anchor relative to a node. For example the horizontal and/or vertical distance between anchor and a node. Often I find changing shapes/paths without changing the anchors along and in many Non-Latin Designs this can cause a long chain of misaligned glyph combinations that are hard to see without extensive testing documents or precomposed helper glyphs.
Just an idea 
That is what the shadow accents are for. I don’t think that connecting the anchor would solve the problem that you need to check if the new shapes fits with the marks.
Those shadow accents don’t work properly in many scripts.
The Mark Preview Plugin helps better in some cases, but it’s tricky to get it showing what you want.
I can explain in detail when we meet again. Particularly I’m talking about SEA scripts like Thai (and Khmer) where you have different versions of marks that get substituted by feature code.
The cloud fails here. Also it is too cloudy
I think it does, because you intentionally put the anchor in a certain place (and in most cases I find that this place is actually in relation to a certain node).