Where is the supposedly attached image gone ?

GT Ondatachange is indeed a change in a text field. that being said the Ondatachange can activate any other element in your title. The title can not check on the value or content of that data. so works for "a value"
Different text fields can trigger their own animations (image sequence) , again it does not check on the value or content of the data, just that it changes in value or content.
Animations include hiding and showing title elements so technicaly no need to trigger the overlay aspect .

One can use pages instead too for different animations.(different image sequences)

if selection has to be based on the text value , then a script can read that and fill the "trigger" textblock ( a datachange) or page to activate the specified animation after making a decision based on the value ( one (check) textbox for checking the value , other per animation for the script to send to as ondatachange trigger for the animation , first option or page selection function based on the (check) textbox value)