If you're looking for examples of problems, RFC7159 (http://rfc7159.net/rfc7159) is a good place to start - just search for 'interop', as suggested by [1]. A quick look at Miscue-js suggests you already check for most of them, but you might still find something new.

[1] http://www.tbray.org/ongoing/When/201x/2014/03/05/RFC7159-JS...