determine which template file a contrib module is using? I'm using a contrib module. It doesn't seem to be using the right template file. I'm trying to triage whether the problem exists in my template or if it is just the hook template suggestion.

What is the cheapest way to debug which template file a particular contrib module is using?

FYI: i'm using the commerce export ftp module. It has it's own template inside the module but i'd like it to use the template file within my theme.

I would like an answer that would be a general debugging practice. Not one specific to this particular module: how do you dump the file path that the contrib module is using? Is the only way of doing so with devel_ui ? I'm looking for a programatic way of doing this.
I thing something like this could tell you what is going on :

$reg = theme_get_registry();
dpm($reg['commerce_order_ftp_export']);