Hi! I’m curious why components can’t use the anchor in the current layer for alignment? Why does it have to come from another component?
Here, the stem is unique, so making it into a component clutters the file; the bowl is reused for d b p q, but it will move around in all 4 letters while you work on it. Why not anchor it? Have I been missing something obvious for years? 
You haven’t missed anything obvious, in any case, I will have missed it for years myself. I just got used to always splitting composites into components, even if a component is only used once (which sort of defeats the point of a component). Would be interesting to hear whether this might be reconsidered for a later version.
Mixing component and paths is dangerous.
I need to think if positioning a component on an anchor in the same layer would be doable. for starters, it can’t align the spacing.
And what is the difference between manually position the anchor instead of the component itself?
You can add a *origin anchor in the bowl glyph. That places the origin to a specific point that may make it easier to align the component e.g. to the left side of the counter, as that parts need to align with the paths.
Well here’s another example.
Say, I want to make this stem component thicker, what my options are?
*origin indeed solves that to some extend, but with big width changes, it will end up somewhere far beyond the bounding box, which would probably sooner or later cause problems with transformations or something else.
So I’d rather just put an anchor to the stem-to-shoulder connection and not worry about any of that. Not having the auto spacing is not a problem, a formula would do fine.
This is a totally different problem but your setup is what I would propose all along. You are using full composite glyphs and with the right anchor setup (#exit/#entry in this case). Everything is always aligned and well.
