The world's population includes some narrow-minded, parochial types, and I doubt that
any qualification (sailing or otherwise) can be guaranteed as "universally recognized".
That said, the RYA
training system has a well-established reputation and its day skipper should be enough to impress most charter companies: especially if you completed the 'tidal' version of the practical course and have also done the associated shore-based theory course.
It's also worth noting that the principal credential required by many charter firms is a credit card.