On pages where the plugin uses it’s own templates…
You’ll need to edit these templates, or hopefully, the plugin provides hooks that will let you modify what is being shown. It sounds to me like the other plugin is displaying the values contained in the custom fields. Image fields store attachment IDs and the actual repeater field only stores the count of rows for the repeater. It is impossible to display these types of fields without using the ACF functions or some other method of converting the values into something that can be displayed.
My first step would be to look at that plugin. I’d probably just start digging through their code to see if I could find any usable hooks. Maybe see if they have documentation. Probably end up trying to contact the authors of that plugin to see what they provide for modifying their templates if I found nothing else.
