Ok, I properly installed the coordinates overlays for goban sizes 11x11 and 15x15.
And I changed the game progression function from
return min ( $total_stones / $board_size * 300, 100 );
to
return min ( $total_stones / $board_size * 200, 100 );
And I changed the game progression function from
return min ( $total_stones / $board_size * 300, 100 );
to
return min ( $total_stones / $board_size * 200, 100 );