What is the issue with the HTML Standard?

Section 6.1 "the hidden attribute" states that when scrolling to a hidden=until-found result of find-in-page, the beforematch event should be fired.

There is no information given whether this event should bubble or not (As I understand that means bubbles=false). However, there are web-platform-tests which test for event bubbling.

/cc @emilio @smaug---- @josepharhar