Sorry to hear your dashboards were overwritten. Grafana provides no way to 'merge' customizations so when you import dashboards they will always be overwritten. For this reason, when customizing dashboards I recommend to 'save as' to your own name.
Regarding a dedicated 7-mode metrocluster dashboard I don't have plans to make one. The reason is some counters don't exist in 7-mode, and while others do exist the effort to enable collection and visualize them is not high enough priority for me right now.
Cheers, Chris Madden
Solution Architect - 3rd Platform - Systems Engineering NetApp EMEA (and author of Harvest)