Instead of using the Salesforce Comments tab, move the content into the native Comments tab. This would solve problems like:
1 - Notifications. If the comments are created as native, Jira will fire necessary events. Also useful for other automation purposes that listen to those events.
2 - Visibility. Salesforce Comments tab needs users to be accustomed with. With the new Jira UI, the tab is now hidden in a dropdown.
A true bi-directional sync of the comments would be challenging and risky to implement, however, we would like to hear your thoughts:
Do you need the bi-directional sync? Otherwise, is static, one-time post of comment sufficient? This means, future comment edits will be posted as new comments.
How important is it to support comment edits in Salesforce?
How would you prefer to mark the comments that come from Salesforce? eg. Add a notice "This comment was made in Salesforce...." in the Jira comment body.
If this feature is implemented, would you still need the current feature? (https://docs.servicerocket.com/salesforce-jira/administrator-guide/setting-up-your-integration-in-jira/setting-up-a-connection-to-salesforce/configuring-email-notifications-to-notify-jira-users)