I tried it from the desktop it seems to work well.
Only, if the customer changes the values too fast; the popup will be refreshed all the time which may cause issues.
This is what triggers the auto update in our script:
$( document ).on( 'change input', '.wjecf-auto-submit :input', me.ajax_update_cart );
Maybe it’s a good idea to work around that. For example removing .wjecf-auto-submit from the form but wrapping the submit-button with a .wjecf-auto-submit …