[Huang 2017] compares the Iwakura Mission with the Burlingame Mission that Qing Government dispatched the first official missions to the West (USA and some European countries) from 1867 to 1870. This mission was in fact organized under the auspice of Anson Burlingame (d. 1870), ex U.S. minister in Qing China (then Qing hired him as an envoy), so its members includes both Burlingame and Qing officials (ministers). Burlingame actually negotiated the famous Burlingame-Seward treaty (1868) on behalf of Qing government during the visit of this mission.

The author unfortunately cites Xu Guoqi, Chinese and Americans: A Shared History, Cambridge, MA: Harvard UP, 2014, only as an recent example of Anglophone scholarship in the article, but I suppose some of the flairs in this subreddit specialized either in Late Imperial Chinese History or in US history like /u/EnclavedMicrostate might offer additional details or literature recommendations on the Burlingame Mission.

He also makes a note that some of the officials published their experiences in the West during the mission after their return to late Qing (so they might be used as primary texts).

Reference:

• HUANG, Yi. "A Review of the Secondary Literature on the Iwakura Mission and the Burlingame Mission." Bunka Koryu: Journal of the Graduate School of East Asian Cultures, Kansai University 7 (2017): 319-36. http://hdl.handle.net/10112/11545 (in Japanese, but also with English summary)