The message that tells us that comments cannot be edited after 5 minutes is like:
Comments may only be edited for 5 minutes.
I noticed that here, the wrong modal is used. The right modal to be used is "can". As it is mentioned here, may is used to ask for permission, while can is used to express ability. Therefore, "can" is the appropriate modal that must be used here. So, the message must be like:
Comments can only be edited for 5 minutes.