it is generally considered a mark of respect for the people involved, and for others, to refer to them by their chosen name, pronouns and gender identity.
The problem with doing that is you end up with a 1984 style "we were always at war with Eurasia".
It's nonsensical to describe someone having transitioned without being able to name the before and after correctly.
The child is still only 14, so I sincerely hope any transition is purely social at this point.