Triggering the change event makes ACF update the _acfchanged you mentioned and may have other effects that I’m not aware of. It was really just a guess, but I’ve been working on projects where I’m extending the ACF JS and where I need to trigger change events after changing values in order to trigger ACF up update conditional logic in fields that also need to be updated because of my changes.
This JS file has a bunch of “experiments” that I’ve done with extending the ACF JS functions. Linking to it because it has a lot of things in it that can help others that might be looking for information on how to do things in ACF using jQuery.
