The market for the Unreal developers could be not that niche as you think if one would trust such reports.
As an employer, I would definitely ignore any certification crap.
A quick glance at the artist portfolio tells much more than some paper than everybody could obtain mostly thanks to paying for certification.
Such paper also tells nothing about the skills of designers or programmers.
It would be just another thing to appear as “expert” in the eyes of those HR people who know nothing about the job they’re recruiting for… So maybe useful for less demanding industries 