Well I thought it worked as I didn’t see the error triggered anymore when changing state of a checkbox but actually it’s still blocked if I try to save a change.
I’ve tried to add that edge rule to bunny and then purge cache but doesn’t seem to work neither 
I’ve also tried to set methodOverride to false or true in the config (as I don’t really grasp fully what it does) but it didn’t seem to fix the issue.
[EDIT]
So it turns out that I needed to broader URLs in condition AND to bypass WAF (that I activated in shield) as saving change was detected as an application attack :
So here’s the working edge rule I found :
