Hello Romain,
As said earlier in this thread, you can’t really choose the specific information for google to show.
But I can tell you how far I’ve get with bubble, I did put the information by double clicking in the index page
And that’s what is displayed in my case when I google the site name. if google chooses a different page will be displayed the specific page description for SEO
Hope it works for you as its for me, and let me know if you find a better way to handle SEO with bubble!