See, the Eldra thing is strange to me. Overtraining exists as a thing in real life and in fiction. From a narrative standpoint, since the minute the MC developed an aura, he has been training and been in life-or-death situations that have forced him to grow. Black Flower mentions that our growth in the time period doesn't make sense, and we know that the spirit brand is a sign of growing too quickly over too short a period of time. Hell, we break our cores by overloading them because we tried to push ourselves too far at the gate. This all points to us probably being the perfect student for Kaito, he is all about pure overwhelming force and physical training, so basically what we have been doing the whole time. Eldra gives us the ability to slow down and balance ourselves. She even states that she would have had us spend time with our cousins had she known they were here. We've been focusing on the martial aspects of life and ignoring everything else. Just look at our reaction to the crates being found on the ships, or us immediately thinking we stumbled into a gate when the Inner Kingdom duo were fighting. Perfection is just as much mental as it is physical. If you're on the JDF route, you're as perfect as can be spiritually and technically, physically, there isn't much she can do for you there. If you aren't on that route, then the Jade Foundation is probably the best one you can get behind the JDF, so again, not much else she can do for you. Plus, just because she doesn't have you hitting a heavy bag doesn't mean her training isn't interesting. She helps you stabilize your transformation, no matter which style it is. So basically, Kaito is a physical trainer, Yang is a spiritual one, and Eldra is a mental one. Plus, it's her first chapter in the story; give it some time, man.