So I've just put the english site into a subfolder.

This will break the IPNs for any subscriptions purchased before the move to a subfolder. Their IPN URL is already stored at PayPal without the subfolder.

For the record I did ask you before moving the site into a subfolder, if that will affect my CBSubs current subscriptions, payments etc, in anyway.

Reference:
www.joomlapolis.com/forum/153-professional-member-support/244040-moving-cb-and-sbsubs-to-a-subdirectory

The IPN URL will be something like the below.

That's exactly how the URLs coming within the PayPal warning notification look like.
Where do I find those URLs within CBsubs to know which ones to reroute?

So for example you could rewrite all URLs to your sites root beginning with /index.php?option=com_comprofiler and send them to your subfolder.

That sounds even better! You mean whatever URL begins with /index.php?option=com_comprofiler gets rerouted to the members/ subfolder?

I didn't know that was possible. That will save me time, because I so far I have have been redirecting the URLs from the PayPal warnings, one by one as they come. How can I do that?

Thanks,

No worries, I have learned a great deal from you!
I'm grateful