I sensed that you acknowledged a distinction. Here the problem seems to me to be that we can know a lot about the tractable part of the matter (pop gen and so on), which has to do with processes visible, regular in some senses, and reproducible. Science through and through.
But the macro- /micro- distinction arose because it was perceived that there seemed to be things happening in the fossil record beyond the reach of the observable mechanisms (henceforth called micro-evolution), partly because they are in the distant past and partly because they seem to involve origins to some degree or other. (How does an arm ever become a wing? How does the exact same pattern of wing in bats appear to come separately in insectivores with echolocation and primates with good eyesight? And why does the stasis/saltation pattern remain in the fossil record even when it is known to give a pretty complete record over time?)
So the “macro-evolution” term is a placeholder for mechanisms as yet unknown - I guess “common descent” might be no worse, but I doubt it is any better, because it’s still covering our ignorance of what may be a multitude of unknown mechanisms, including (to some unspecified degree) the genetic processes we know and love, then all kinds of exotic “natural” processes from hybridization to emergent laws of form or saltations, up to special creation of … something … be that an entirely new organism or a few key mutations.
In other words, we can’t (usefully) simply define our distinction as something precise like “everything below species level is micro, and everything above is macro.” As we all know, “species” is a slippery concept, and microevolution might be capable of producing some of what we term species (I’m thinking of the way that bird races have been split into species recently on genetic grounds), but not others.
Until we have a better fix on mechanisms, we’re not even sure what it is we’re defining, apart from recognising the valid suspicion that there’s “something out there” beyond the old population genetics extended in time. It’s interesting, for example, that some of Richard Buggs’ and Paul Nelson’s work on Orfans has (at this early stage) hinted that there may be commonly a true natural distinction at the level of the genus. If that kind of thing were confirmed, it would be a focus for research on what a genus actually is, and how they arise - but neither “common descent” nor “macroevolution” would be of much further use in describing what’s going on.
I agree that your example of YEC whales from ungulates microevolution is not useful unless we grant that everything is, after all, microevolution. That kind of thinking seems to hinge on this concept of “kinds”, which given how few kinds are in the biblical data (for example, 3 kinds cover all animals on land, none of which are whales, which are created, in old translations, on a separate day) is to me an arbitrary scientific category.
The whale example, though, provides another category of “macroevolutionary” mystery, which is the apparent long-term teleology involved in such a transition, for which neither neutral theory nor adaptationist Neodarwinism seem a good fit. Instead of arterodactyls getting by by being “good enough” in a marine environment, it’s as if they were handed a spec for perfect adaptation to deep-water life and ticked off each modification as they achieved it in a program uninterrupted by dead-ends, climate change, etc. Sea-otters work well enough - why become a blue whale?