这句话中是否缺少了介词

This will allow the chorus of young and elderly Anglo-Saxons toas百度竞价推广ble on the side stages either side of the seating block, more or lessunseen, ready to take the action further, playing across the horizontal plane.

请问老师，either side of the seating block 前面是否应该有个 on 或者有个“逗号”？either side ofthe seating block是对the side stages的补充讲解对吧？

谢谢老师！

我理解应该有on才准确，on either side of the seating block 应该是定语修饰side stages.