Obviously it isn't ideal to have someone non F trained serving in F - and that is very much BA's issue to sort out. However, what were the alternatives on the day if no F trained standby were left available? I think if done with the right intention and the cc member was genuinely trying to do her best (which is sounds like from the OP's story) I would be ok with that.

I am more concerned with supposedly F trained crew who simply can't be bothered