Is your current bike an incorrect fit? If so, it should be what's addressed first.
I would disagree that the new bike must be carbon, that's absurd, but sure- proper fit is a priority over a power meter.
If your current bike is an excellent fit, then why do you need a new one? Has the coach specifically state why a new bike is needed?...it cant possibly be just due to yours being an aluminum frame since, as stated, that would be absurd.