help with translation

Hi.
I am using the theme fruitful in Spanish because I think much better than any premium theme .
Good work and congratulations.
My apologies for my English because I’m using google translate .
My case is the following:

The theme does not show all the words in Spanish , many are in English ( See Photo 1).
Fruitful.pot to download the file and open it in the poedit I see that has 408 lines of text and es_ES.po file shows only 237 lines of text .

I want to finish translating the fruitful.pot missing file while retaining the 237 lines that are already translated lines .
How can I do that?
Can I translate the .pot file missing lines , generate the .po file and then attach the latter with which come with the fruitful theme ?

I appreciate your time and response