Thanks. I was hoping for a built-in solution.
I already have an ACF field for every author bio (one for every language, so I made a filter and show the correct one depending on the language of the blog:
add_filter( 'get_the_author_user_description', 'filter_the_content_in_the_main_loop', 1 );
function filter_the_content_in_the_main_loop( ) {
$blog = msls_blog_collection()->get_current_blog();
$alpha2 = $blog->get_alpha2();
$field = ( $alpha2 == 'en' ) ? 'short_bio' : 'short_bio_italian';
$author_id = get_the_author_meta('ID');
$author_field = wp_strip_all_tags( get_field($field, 'user_'. $author_id ) );
return $author_field;
}
posting this in case someone gets to this post in the future