I'm not an expert, but the Boxer Rebellion occurred in 1898-1900, towards the end of Queen Victoria's reign. So, if IHMN is about Victorian-period gaming, they should be quite appropriate, especially since the clothing of the more civilian-looking ones should not have changed much since decades (or even a couple of centuries) beforehand. Also, any that are wearing queues should be fine until the end of the Qing Dynasty in 1911/1912.