Given all the resources available to him, Samuel Couling did an excellent job with his Encyclopaedia Sinica (1917). However, I couldn't help but note that some entries were surprisingly short given their importance in Chinese culture. I've listed the shorter entries that could have a been a bit more detailed (in my opinion anyway) and one omission. To Couling's credit he did include a great many articles related to missionary activity so that even the most obscure religious group is likely to have been included in his reference work.
1) Bird's Nest - interesting that Couling had more to say about bird saliva than rice gruel. But given that bird's nest is considered a delicacy, I think he could have done a bit more with this one. Perhaps commenting on the perceived health benefits or efficacy.
2) Congee - the humble dish enjoyed by Chinese all over the world, including myself when I'm sick (though I'm not Chinese). What's more, there are several shops around Hong Kong that are famous for their congee. The last time I visited Hong Kong International Airport there was a new restaurant inside that specialized in different kinds of congee. Couling doesn't seem particularly keen on it though as he only devoted 5 short lines of text to the subject.
3) Filial Piety - for such an important Confucian concept, Couling includes only a brief paragraph here. Walking the streets of Hong Kong or mainland China, it's still quite amazing to see how strong the practice is, having been passed from generation to generation all the way to the 21st century.
4) The Five Classics - the works are listed but nothing else about their use in the imperial examinations (科舉).
5) The Use of Chinese Herbs - nowadays referred to as Traditional Chinese Medicine or TCM. This omission is perplexing because Couling was certain to have heard about, and likely to have seen, the of use Chinese herbs when interacting with the local population. Couling has entries for a few varieties of tea, as well as the lychee and the longan, two fruits popular with the Chinese, but no herbs. In present day China, the use of herbs is a regular occurrence. In Hong Kong there are many medical clinics devoted solely to the dispensing of Chinese herbs for conditions such as fatigue, headache, cold, etc. Because the practice and use of Chinese herbs involves the Chinese concepts of hot, cold, wet, etc. perhaps Couling thought of this in a different way. Also of note is the absence of moxibustion, a form of treatment associated with Traditional Chinese Medicine.