After doing my first 20 tribunal reviews, I have some feedback for Riot.
1. Without a replay (that I could hopefully watch up to 10x speed), it's hard to tell if the things in chat are true. For example, intentional feeding.
2. If there are multiple reports, could you indicate if the reporters were all in the same party? If the chat says things about intentional feeding from two people then I tend to believe it. If those two people came into the game together, however, then they probably are just supporting each other.
3. The feedback from a Punish vote would be more useful if I could indicate which reports caused me to cast that vote. Sometimes half of the chat logs won't be that bad. There will be some that go over the line, however, or some that suggest they started to feed intentionally. While you shouldn't require extra comments in a tribunal review (it'd definitely reduce the amount of reviewers), it should be an option for those who want to help.