Does anyone know of a way to specify the comment author when creating comments in Jira?
That is unfortunately not possible to do. I just had the same issue when integrating the Product Feedback comments into our internal Jira. What I ended up doing is putting a line at the beginning of the comment as Comment by: Tyler Lamparter.
You can see the Jira idea here: https://jira.atlassian.com/browse/JRACLOUD-35124