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It's possible to manage comments by using "Manage" button (3). After clicking it you will see a prompt similar to the presented below:
Please note that a comment is to be added to an issue that is currently marked in the Excel spreadsheet (see above images). When you select multiple issues in Excel and try to add commen tin comments in bulk, there won't by any action after pressing "Send". Each newly added comments are to appear below the previous one. Horizontal line is used to separate added comments from one another. Each comment is added in a name of a currently logged in the add-in user.
After typing a comment and pressing "Send" it is to be added to the issue.
Whilst being in a selected issue tab, you can also monitor current state of an issue (4) and if necessary, immediately modify it by using "Transition issue" with its drop-down menu selection (5). After selecting a desired status, one can expect a confirmation prompt:(TBC)
Be advised - all changes will be discarded if you haven't used "Send issue to Jira" button.
In a similar way there's a way to change single issue type (6).