Arifur,
1. Check whether you have those text keys in admin panel. Use following URL: yoursitename.com/admin/dev-tools/languages.
For example your missing text key ( last screen shot) is base+comment_form_element_invitation_text.
Go to yoursitename.com/admin/dev-tools/languages and search for comment_form_element_invitation_text. Check "in keys" checkbox.
2. Go to admin panel>>languages>>click "save" without doing anything. This will generate language cache and might help to solve your problem.