Problem being it only returns information about highlight properties and not if highlight occured in an event. It's nothing like what I'm requesting above as far as I know.
This is what the current $highlight identifier does:
Returns $true if highlighting is turned on in the Highlight dialog, otherwise returns $false.
Returns the Nth line in the highlight listbox, or if text is specified, returns the properties for the highlight line that matches text.
Properties: text, color, sound, flash, message, nicks, regex, cs