@mbunkus thanks for the report.
About entering an IPv6 address for NFS in XOA: did you put the  around the IPv6?
If so and it still failed you can indeed create an issue on vatesfr/xen-orchestra repo (make sure to reference this thread if you do).
For the rest, no need to create issues, i'm aware of them and I'll note them in our internal board for next devs. 🙂