This is just spelling / grammar, I have no problems with these errors, especially when the main documentation is wiki-based (this may be because I'm not a native speaker). In my limited experience with Facebook docs before the Open Graph API, I haven't seen factual errors, but there are a lot of omissions.

Open Graph API seems very clean and it also seems like it doesn't need much documentation... if the API calls actually worked. I haven't used it and I don't plan to start using it given these reports (in the old API there were also quite a few things that break occasionally and take forever to be repaired).