I'm not sure the conclusion that Chinese people might not understand Chinese either is the best counterargument to Searle's thought experiment or its conclusion effective use of words alone doesn't constitute sentience. At no point does the difficulty in establishing what Chinese people do and don't understand rescue the possibility the non-Chinese speaker knows what's going on outside his room, and most of the arguments to the effect that Chinese people understand Chinese (they map real world concepts to words rather than words to probabilities, they invented Chinese, they're physiologically quite similar to sentient me, they appear to act with purpose independently from communication) are also arguments to the effect that text-based neural networks probably don't.
In a trivial sense, it's true I can't inspect others' minds, and despite what everyone says I could be the only thinking human being in existence. But I have a lot of reason to suspect that physiologically similar beings (genetically almost identical in some cases) who describe sensations in language they collectively invented long before I existed which very strongly matches my own experiences are somewhat similar to me, and that an algorithm running on comparatively simple silicon hardware which performs statistical transformations on existing descriptions of these sensations written by humans is simply creating the illusion of similarity. Heading in the other direction, humans can also be satisfied by the output of "article spinners" used by spammers to combine original texts and substitute enough synonyms to defeat dupe detectors, but I'm pretty sure the quality of their writing output shouldn't be given precedence over our knowledge of the actual process behind their article generation when deciding if they're sentient or not...