Yup. The big question that should get answered is what the precedence order is, since Arduino has…surprised us on that front before. If you put something in the sketch directory and it’s also in Arduino-Boards, what happens? And does the coommandline behave the same as the IDE?
Arduino has, we believe, changed the build order on us before. The current documentation for search path ordering is buried in the commentary on some pull requests that proposed changing it.
I suspect the right way to figure this out is to enumerate all the possible places a library might get placed and write a script to compile a sketch with different versions of the library in each place, testing out every possible permutation. That’d let us autogenerate truthful docs and also catch potential changes.