French translation not always working

Hello,

I run a french website with the Freely theme.
I wanted to translate the theme for terms such as “comment” “read more” and so on in French but the .po file for French, I added (in the main theme folder even though I use a child theme for it didn’t work when I placed it in the child theme folder) doesn’t work for all the terms (not working for Next Previous in the navigation or ALL for the portfolio category).

What dit I do wrong, or should I modify php template via the child theme ?

Thank you