Change this code:
add_filter( 'generate_blog_columns', function( $columns ) {
if ( 'review' === get_post_type() && ! is_singular() ) {
return true;
}
return $columns;
} );
to this code:
add_filter( 'generate_blog_columns', function( $columns ) {
if ( ( 'review' === get_post_type() || 'buyer-guides' === get_post_type() ) && ! is_singular() ) {
return true;
}
return $columns;
} );