SLA-"Comment: For Customer" field

[Richard Imbrogno]

Hi. I am looking to create a project automation rule based on SLA Threshold Breached as the trigger

The SLA condition is very basic. If the ticket is not updated after 21 days I want the rule to add a comment to the request that asks the assignee to provide an update to the request

1. For the first 21 days, it the clock will start when the ticket is assigned. From that point the Assignee needs to provide an update at least every 3 weeks by adding a comment. In some cases the assignee will not share the comment with the customer though. He/She should not be penalized for this but i'm concerned that the system will not acknowledge the name of the SLA Start condition is called "Comment: For Customers" 
2. Assuming I can successfully do this, once the comment is added via the automation  system clock be reset to zero and start a fresh 21-day cycle.

For condition 1, does the comment have to be shared with the customer? For option 2 if the automation creates the comment will it reset the clock since the trigger is not made by the assignee nor the reporter

Lastly, this just seems to be way more complicated than it needs to be. Is there another way to do this. Thanks.