Suppose I am sending money by international wire transfer from my FDIC-insured bank account in the US to my CDIC-insured bank account in Canada. Suppose one of the banks become insolvent during the wiring process. What happens to the money I sent? Is the money insured while in transit?
The simple answer is that the wire transfer process has handshakes which guarantee that the transfer either happens or doesn't; if incomplete it is cancelled.
I don't know whether that protects only bank to bank or fully account to account.
But I think you're at more risk from a bank's servers blowing up in mid-transaction than you are from bank failure; the latter will be an organized shutdown of a system designed to handle that robustly.