I have a site with a master language (en).
I have a page (es) already translated by a translation project. Then I update that page from my master language (en).
The launcher generated is full in English. The translator provider should translate full content again if they do not have a memory translation.
Is there a way somehow I can send only the content modified in my page, I should not pay for the translated content again?
Just to confirm, is the product that you are working on AEM Mobile, or AEM? They are two different products, with next to no overlap.
Since you used the word "site" I suspect that it is AEM.
If it is AEM Mobile, stay tuned for an answer from that team.
If is is AEM, I suggest asking in the AEM forum.