Hey Jose,
the Google Font insert code is contained in the “header-functions.php” file in Ikebana (right at the top), and it does include all possible font-weights; at this point it is worth noting that not all Google Fonts come in different weights, e.g. Lato only has two possible weights, 400 and 700, while Open Sans has five.
To change the font width of masonry elements, you can use e.g. this CSS:
.iso-masonry .post { font-width: 400; }
Sincerely,
Andrii / Satori Studio