Tell us what you are trying to do? We have alsways big issues translating stuff, there is a way to export in columns on a google sheet so that client can easely trasnlate stuff? We will then translate manually from wpml advanced translator but we need a way to collect the missing translations.
An example is that, we have main language in Italian and second languege in English, would be handy to be able to export a excel or something with 2 columns, first italian and second english so that client can easely fill the document.
Is there any documentation that you are following? no
the only way to achieve something similar is to export XLIFF file, when you open it in CAT tool for translation, you will see original and target language. The downside of this is that you can not combine different translation methods, you can translate via XLIFF and also use WPML editors, as it will not share translation, etc. You need to use the same method.