You could try to run poedit on the plugin to see if there are untranslated strings, but it seems related to the use of child-theme template file.
Maybe a quick fix could be to copy the lang files into your child theme folder too and see if it works (you will probably need to change de text_domain for each strings and generate a new lang file for your needs).
I’m not very familiar with child themes and plugin template files, sorry.