I actually think "construct" much like "disorder" is a kind of marker for an improper noun. Both are so formal as to suggest that "adjective adjective construct" is a formal term. Such improper nouns, I think, are less insidious than improper nouns without such a marker. Because they are easier to detect.

If the "highly sensitive person" were instead called the "highly sensitive personality construct" it would be much less confusing as an improper noun. It is clearly unwieldy here, but that is partially down to construct being too vague, and presumably down to me only spending 10seconds on the name.

As an example of how "disorder" helps suppose that "Persistent depressive disorder" were instead called "Persistent depression". That would clearly be much more confusing.