I have a suggestion.
You can give the capability to the user in specific comments to give permissions which user can see it and for the other can be hidden. Of course default is all and then you can pick.
I suggest this Idea because we constantly have a minor problem when in one task there is collaboration between managers and employees. The problem is that we can not say all thinks public. For example "i do not like his presentation but lets give me a second chance etc etc. So we change messages in Cliq and those conversations get lost in million other thinks.
So when we want an archive of all this we found a hack. We encrypt the text in comments with sensitive data and we post the code For example if you paste this code
Z5kIOOgFPt9w+wPjkLdQqkjYOwt3F8qx0VSHnTZKlA== in the site
https://codebeautify.org/encrypt-decrypt you can see what i am saying.
This could be also an easy solution to embed in your comments but has disadvantages. It is not elegant, you have to use other apps outside zoho, If you want to see what you where saying in the past you can not search and others. So we use it to discuss only very important thinks that we want as archive on the task after the task will close. Last but not least is that the other users know that you are saying something that you do not want them to see.
Anyway this is a feature that no other task management program has (as far as i know) and i think that can give to Zoho projects extra power to make the managers to use it. Keep in mind Zoho team... the managers are the decision makers of corporate purchases so you may want to push this idea to your sales team. I am sure that they will like it...