The draw.io apps for both Confluence Cloud and Server/DC allow administrators to mass import and convert Gliffy diagrams in an instance.
The original Gliffy diagrams are not changed in any way, so reverting the page to a previous version will correctly display that page at that revision.
- Make sure your Confluence and draw.io app versions are both current, and reindex your instance so that no diagram files are missed.
- Run the mass import on a Server/DC test instance before doing it on your production instance. Test individual Gliffy diagram conversions by downloading the .gliffy diagram attachment and dropping it into the draw.io diagram editor.
- Perform the mass import as an administrator who has write access to all pages, outside of working hours.
At this time, there is no mass import for Visio diagrams.