2012-05-01: Support was added for Waymarked Trails. (Other news...)
Requirements
what are the requirements for Translation reviewer?
They're not set in stone and Siebrand or Nike can answer better, but in short and based on what they said in the past: 0) knowing what it is (see here), 1) needing it to do some work (e.g. "I plan to go through all MediaWiki core messages to ensure consistency"), 2) having an adequate experience as translator here, 3) having an adequate track of interaction with other users here (this is a tool to enhance cooperation and feedback).
At least to be a native speaker with a larger number of contributions, or other software localisation credentials. As you have indicated that you are a native speaker of English, I'd say that having you as a reviewer would probably not be the best idea. Reviewer can give the right to other reviewers, so it's meant as a peer trust based right eventually.
