Thank you John,
Clearly this is the situation when one of us knows what he is talking about and the other one doesn’t. To be clear: you are the one that knows! 🙂
I am afraid your reply left me none the wiser. Is this something that could be tackled through functions.php? I think you are suggesting, and this bit I get, is that the issue is around the input being split into words and then doing a LIKE query on each word, which is what WP apparently does. But that this is not what’s happening with ACF? How do I tackle it?