That'll work only if the Tribunal is completely diverse. Knowing the content author could and will also promote bias.
You can hide and author's username, but not the content and style. It's still too easy to figure out who the author is.
Just pointing out more issue's so we can do a better job.
Your description here is definitely a start.
Interesting - I had not thought about recognising a downvoter's writing style in his downvote comment.
While it is possible that this could be recognised, I personally don't view this as a reason to avoid this solution.
a) it is possible to write the downvote comment in a manner such as to disguise one's style
b) with thousands of members, it is impossible to be sure, even if you suspect you recognise a person's style: I don't think it will be easy at all to know who the downvoter is
c) people are already sometimes trying to guess who the downvoter is, and retaliating by downvoting on the suspect's posts, even though there is a good chance they are attacking someone who had nothing to do with the downvote. With the proposed system, they instead can simply appeal the downvote, and if it was abusive, they can be certain the right person will receive a penalty.
d) with this system, if the post author thinks she knows the downvoter from their comment style, and then abusively downvotes them, she herself will be appealed and penalised.