There is nothing that anyone can claim about anything which does not manifest. If it doesn't manifest, how can anyone observe it in order to know anything about it?
You can hold a qigong pose and feel heat on your palms when you concentrate on them. Is that chi? What is chi? Define it.
So far, nobody has shown that a metaphysical definition of chi (as a "force") is real. There's no reason to believe in it other than as a mental tool for improving yourself in some way.
Is it helpful? Then use the concept. But just because it's useful, don't think that makes it real.
The only way to read that kind of stuff which you know is based on ideas that are unscientific and wrong, or language from a time when science wasn't a thing, is to see what conclusions they make about how best to live / practice, and then see if it confirms what you already know. How they got to those conclusions is pretty well bogus, or at least there's a better, modern explanation for why it worked out well.
And maybe if you understood the scientific explanation for why it works, you could refine it and remove the bits that don't add anything or which make it harder to do.
Hope that helps.