When I did SEO tasks for overseas clients/PMs, I found it very easy to not tell the truth to the clients or simply cheat them, and meanwhile offer them a perfect-looking sheet with useless or even harmful keywords the clients would never be aware of – I just never do it that way. And this is not only due to language barrier, but because of some specific steps in SEO processes like keyword research.
For example, some acronyms could be very deceptive, like “ECM”. This term is usually used to mean “Enterprise Content Management” in the west, and also “Engine Control Module” in some cases; but in China, things are very different, people mostly use it to refer to the latter, and rarely use it for the former.