So far all the checks that can be performed by coder.module involves extra .inc files. The checking data returned by these modules is rather obfuscated compared to how it could be. Extensions such as the 4.7->5.0 upgrade use this code to return the rules return array('upgrade47' => $review);. From an API standpoint, that doesn't make much sense. The function coder_EXTENSIONNAME_reviews() should return just an array and the module should integrate it into whatever data structure it wants.