Re: can I change (and how…) the word ”home” in the nav tabs? (in according to SEO)
‘Home’ or ‘Index’ are two very accepted conventions in web sites denoting as they do the domain site root or initial main page, I doubt you will gain much in SEO terms from changing them, often there is too much emphasis placed on suppossed SEO enhancements.
However if you must di it 
then read through this page for a better understanding oof the approaches you could take:
https://codex.buddypress.org/how-to-guides/customizing-labels-messages-and-urls/
But yes you could change the string as seen in the main header.php nav
