Hi there, @nikola_colls ...
Thanks for posting a link to this idea. As you may or may not know, the idea process that allows Canvas users from all over the world submit their own suggestions for improvements is undergoing some changes. As you've seen from the idea that you linked to, commenting isn't currently enabled. I'd encourage you to bookmark that idea so that you can follow it if/when commenting becomes available (I'm not sure when that would happen, though). Also, I'd suggest that you read through Turning Your Feedback into Better Prioritization a... - Instructure Community - 637959. Finally, I'll just include these Guides for your reference and for anyone else who might be reading your posting and my response:
I hope that these links will be of some help to you.