I don't know if they're all running on the same machine / virtual machine, but on the occasions mytrezor.com has been malfunctioning - balances not showing - test.mytrezor.com has worked fine.

Given that satoshilabs also operate dev.mytrezor.com, perhaps one of the testnet servers could be converted to a backup mainnet server.

It may be that the BoP backend has unresolved issues when running on mainnet that do not occur on testnet.

Edit : This is the 4th time i have seen myTrezor.com BoP back end crash. On the first occasion test.mytrezor.com was also broken, and if I recall correctly it remained broken for over 1 week after myTrezor.com came back.