Explanation of the English in this University of Cambridge graduation certificate
This is simple reversal of clauses: see this question. If it helps, you could imagine a bracket after 'was', and a close bracket after '2016'.
(I also think that using the Free Dictionary to validate the syntax of the University of Cambridge is equally back-to-front, though in a less literal sense.)
One of the answers seems to suggest that it's a case of locative inversion, though I don't see it. I'd suggest that instead you have a complement to the noun congregation consisting of two asyndetically coordinated phrases headed by verbs in past participle form. I.e.,
