修炼 = (of Taoists) to practice austerities / to practice asceticism I don't know what this has to do with the transformation of animal spirits. This kind of practice is for transforming the human spirit. 修行 = religious practice (Buddhism)

The loose translation of the above words would be training or discipline in the noun form. As you are probably aware, not all words can be directly translated into another language. Often, part of the meaning is lost after being translated. The meaning of the phrase in English would be somewhere along the lines of: → Undergoing refinement of self (to ascend) → Spiritual self-cultivation → Divine meditation ... in the spiritual context. → Self-improvement ... in the general context Hope this helped ☺

I would consider two terms: "spiritual hibernation" or "spiritual chrysalis" A chrysalis is the outer covering or cocoon of a butterfly before it emerges. It is also used as a metaphor for any transformation, physical or spiritual.

我也想知道~