A few comments:
Multiple proofreadings might be advisable in such a system, which would put a pressure on time
What happens when a non-native speaker corrects something incorrectly to another non-native speaker?
What happens when people are reading texts in areas they are not specialised in?
How would you deal with the problem of people not reciprocating?
I don't want to sound negative as I think there's the germ of a good idea here, but I have taught post-graduate students and think there are some issues that might need ironing out for it to work effectively.
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