Missing Æ and Œ smallcaps
The ae.sc and oe.sc glyphs look like placeholders, and need to be drawn properly.
In Roman, what's ae.sc.alt01 supposed to be?
Not sure what that placeholder thing is, sorry. I don't remember making it, but then I don't remember much that happened five years ago.
I suppose an appropriate use would be a ligated small cap Æ, whereas the regular small cap is a broken-up AE. Thoughts?
I don't think that would suit e.g. Danish, where I think Æ must be a ligature. My hunch is for both ae and ae.sc to be ligatures, else why provide them in the first place?
If I had to guess, I probably got the justification for breaking them up from some long gone ivory-tower Typophile thread. I don't recall what it was exactly.
You're absolutely correct about Scandinavian orthographies requiring them though, so it's Kate 1, Seb 0. (Well, probably more like 5-0, by now.)
Us 6, World 0 :)
Too heavy at the joints?

Maybe, by the slightest bit? I don't see anything wrong with it besides that though.