You can absolutely do more with harmony and balance and time stopping than yoga and feng shui as a training method.
I think you're misunderstanding my argument. My argument isn't that Eldra's foundation doesn't have amy requirements, my point was that the training felt lackluster and underwhelming because those requirements don't feel all that difficult to achieve.
You can argue that getting a yin and a yang alignment is ultimately based on your environment - but my point is that those requirements have nothing to do with who the MC is. There's no struggle involved, there's no trial to overcome (at least none that are elaborated for more than a page or two), there's no lesson to be learned so it just feels utterly empty.
If you do Zhao Yang you are travelling the empire and siphoning power from lost relics. If you are doing Kaito, you are literally dying over and over again. If you do Eldra, you're doing yoga and feng shui - and she's really, really strict about it.
One of the three is just less interesting. And it's not hard to tell.