Note I have not used wix, In my example below we use Jquery.
wix may have its own flavour of jquery that you need to use or override.
In fact I see that you are using wix's jquery $w( )
Having a quick look at the wix editor API
it looks like you may be able to use onViewportEnter( ) instead of waypoints.
You should still be able to add postMessages
Adds an event handler that runs when an element is displayed in the viewable part of the current window.
An element enters the viewport when the page is scrolled to show any part of the element. An element also enters the viewport if it was hidden or collapsed and is then shown or expanded in the viewable part of the current window. onViewportEnter() is not fired for hidden or collapsed elements even if they are scrolled into view.
Deprecation note: The $w parameter of event handlers is being deprecated. To get a scoped selector for working with elements in repeater items, use the $w.at() function and pass it the context property of the event parameter: $item = $w.at(event.context) . To learn more, see here.