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Most limitations arise from the way the app has to add the signatures. Because the Atlassian Cloud API does not offer an option to modify comments before they are stored, the app can only edit them afterwards.
Delayed update in user interface
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The Jira notifications include who edited the comment. When the app adds the signature, the notifications mentions the app as the editor. This can probably be changed of if you have access to template editing.
Interestingly, the customer notification notifications work differently, and they mention the user, not the app.
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