Due to specific of data storage in in Server/Data Center environment and drastic difference from current Template structure on Cloud - we don’t support automatic migration of existing templates from Server/DC to Cloud.
However, there’s a proper workaround possible.
How to migrate Easy Templates to Cloud from Server/Data Center
While on Server/DC - Create Jira issues and it’s related structures from existing templates on you selected Jira project(s)
Use all the Templates you want to migrate to Cloud
Proceed with your Jira migration path according to the defined plan using selected tool https://www.atlassian.com/migration/plan/cloud-guide#migration-tools
Install Easy Templates for Jira Cloud https://marketplace.atlassian.com/apps/1219112/easy-templates-for-jira-issues
Once your Projects and Jira issues migrated to Cloud - re-save tickets (=re-create) as the new Templates on Cloud.
Now you can use your Easy Templates for Jira again!
Or drop us email firstname.lastname@example.org