More protein won't induce molt.. reduced protein (or nutrition/intake) MIGHT. Or will it?! Yes, in my experience (hair loss after bariatric surgery) and also done commercially to maintain production schedules. But is it necessary??
Reduced lighting can be used to induce molt.. another commercial and usually otherwise natural process.
You're fighting genetics here rather than something you've caused, IMO, since this one is the outlier. They haven't read our books about what they "should" do to be considered normal or average.
Even when a bird does molt, they don't always molt out or replace the feathers we think they should, again in my experience.
Hope she molts soon enough and continues to thrive!