Not a coach either here, but I’m an acceptable age group triathlete who has been coached before.
Depending on where she is in relation to her race and the distance she targets, that plan is not unreasonable. In fact I’ve just reviewed Joe Friels Triathletes Training Bible and he talks about how it can make sense to progress long or ultra endurance athletes towards more specificity. For half and full distance triathletes that specificity is basically a crit or road racers base, meaning we could progress from a good dose of short power workouts towards more sustained efforts. I’ve followed such approach in my running the past season with pretty good results (progressing my weekly interval runs from 400 to 3000m).
Clearly all that is very individual and if she can’t complete her workouts the plan can not be effective. It might be however that she has just uncovered a long neglected part of her power curve or that she is overtesting on the ramp.
If the plan does indeed progress through short towards more sustained efforts I would give the approach a chance, but review testing protocol and workout intensity.