I'm not sure what board is appropriate for this discussion topic, so I'll post to site talk. And maybe there has been a similar thread already.
Last month I was doing research for restaurants in Paris. I got a good deal of feedback and advice from posting on the France Chowhound board. But it occurred to me that a large number of active posters on that board seemed to be US transplants to France, and seemed to know each other (not to imply that they do not have food knowledge about France --I discovered quite the contrary, and greatly appreciated their suggestions many of which I followed). Yet, I couldn't help but wonder if I would have gotten different ideas/suggestions/recommendations from a similar sort of site but that is French-language.
Similarly I read a post from someone asking about where Italians like to eat when visiting NYC. The poster posted to the Manhattan site. I thought, why not post to the Italy site and ask the Italians? Someone else had made that suggestion, and the response was that the Italy site is mainly English-speaking tourists looking for recommendations in Italy.
In general, in non-English-speaking countries, posters to CH will be a much more "selected" sample, limited to English speakers, mainly with experience with US restaurants and dining habits.
This has made me think about CH are a source for restaurant recommendations: I'm much more likely to exclusively rely of CH for trips within the US, but much less likely to rely on it exclusively for trips to other countries, but rather would treat it as one of many sources.
Interestingly, I found a couple of restaurants in Paris with comments on TripAdvisor in both French and English. In my highly unscientific sample of 2 restaurants I happened to be looking at, English speakers gave more "stars" to these restaurants and more positive comments compared with French speakers. Not unexpected, I suppose, but suggestive of a possible differential in what gets recommended and what doesn't depending on who does the recommending.
Is there a French language CH or equivalent? (La Fourchette, but that is not quite the same thing.) An Italian language CH or equivalent? Perhaps the nature of the restaurant and dining habits in these countries (and others) limit the utility of such a site: in the US, restaurant comings and goings are probably much more frequent, leading to a more vibrant basis for discussions/recommendations.
Just my musings. Now I suppose I should get back to work :-)