Subscritpion form not working in non default language browsers

subscription form is being included with an iframe in the landing page, polylang is being used. The problem is that is not working in browsers/devices other than spanish language as default. Subscribers cannot sign up from Ireland, Belgium or United States.

Even if using a different form for english version.
I thought it could be a polylang issue, but I have read the plugin is not supported, but what happens it doesnt trigger the difference between both languages. It is occurring with french and English language browsers/devices

We can subscribe users with no problem with the same data they are inputing.

I would appreciatte any feedback. Thank you !

The page I need help with: [log in to see the link]