I would be careful about what you say. I've been riding for over 15 years, and it is always very disheartening to see someone who's still a beginner try and work with a horse that's too much for them at the moment. Honestly, when I got my first horse, I took things people said the wrong way sometimes. He didn't have any big issues, but when someone would say something, I would get defensive. I learned that for me, if someone thinks that I may need help, or could do something different, I always listened better if someone said "hey, my horse used to do that, and I did x which seemed to work well, maybe it might work for her", or even just starting up a convo with me, about the horse, and putting in your training thoughts at the appropriate moments. But I would not go out of your way to watch her, and point out when she could do something different. It's true that when she has enough, she'll definitely let her know, and it may be hard to watch, but that might be the best way for your friend to learn. It took my horse turning into a complete witch, for me to realize that I needed to switch trainers, as my current trainers methods did not work well with my horse. Good luck, and hopefully things will work out.