It's true that on Azure we require both the resource group name and also the Virtual Network name to be in lowercase.
But Microsoft names are case-agnostic, so this should be okay.
We've had other customers with this issue before and converting the resource group name to be lowercase worked for them.
Also, sometimes technical restrictions exist for internal reasons that are not obvious / hard to share externally. :-)
That said, I shared your message internally and someone is looking into this. Stay tuned. More soon.