@jenkinhill, it's not true that the current collation have no trouble. I wrrte for some website a component to use Google cloud translator and sometime the returned string fails because collation(the site have hebrew and Arabic language and the customer use many spécial chars) and return mysql error 1267, and this is a collation error.
I added a UTF8 checker
$isUTF = mb_detect_encoding($translatedText, 'UTF-8', true);
and this check for strict UTF8 validity but mysql cannot save it, so i think that EvanGR is right, but i dont know if changing to utf8mb4 solve the issue(read the full comments on the linked article).