>The only word doing any work at all in that definition is "artifacts"
That's the subject, the only word that is NOT doing any work there (since both regular and software engineering produce artifacts).
Words that do the heavy work in that phrase are:
structured,
mature,
legally enforced,
standards-based approach
- for
repeatable,
reliable,
verifiable,
- artifacts
- under stable external constraints
Software can sometime appear to touch those.
E.g. there are "standards", like HTML or like ARIA, so it's "standards-based" too! But those standards are loosely enforced, usually not mandated, loosely defined, and ad-hoc implemented with all kinds of diverting.
Or e.g. software can some times be repeatable. E.g. reproducible builds (to touch upon one aspect). But that's again left to the implementor, seldom followed (almost never for most software work, only in niche industries).
In general, software is not engineering (in the strict sense) because it's anything goes, all the above conditions can or cannot be handled (in any random set), the final work is a moving target, and verification is fuzzy, if it even happens.
>The reality is that engineering is the methodical application of constraints to solve a problem.
In that case, following specific constraits to solve a math problem, or to draw an artwork (e.g. using perspective) is also "engineering". That's too loose a term to be of any use.
Even accepting that, the degree of "methological" in software "engineering" versus e.g. civic or aviation engineering is orders of magnitude less.