Translate layered nav

Hi!

I have different sites in different languages which all import products from a common file (in English).
I am not being able to translate the layered nav: http://i.imgur.com/U88o5Dq.png

I’ve read the official doc but as this isn’t a static stream it seems the POT file doesn’t cover it.
Also tried this: https://www.speakinginbytes.com/2013/10/gettext-filter-wordpress/

But no luck. Any help?

Thanks a lot