Migrating from Confluence Server & Data Center to Confluence Cloud works seamlessly. Simply export a page, space or entire instance and import to your Confluence Cloud site. When you install the Cloud version of the Custom Jira Charts for Confluence app your charts will be configured exactly as before.
Note: Charts with User Impersonation enabled will be imported with User Impersonation turned off. This is to ensure that Custom Charts are secure by default and, therefore, charts must be edited and re-assigned an Impersonation User after importing.
Before migration, navigate to the Custom Charts - Settings and register for the migration using the grey button in the screenshot below.