Spiritual energy doesn't exist, there is only spiritual power and spiritual pressure.
You know what I mean, don't be like that. When I first watched Bleach in my native language with fan-dubbing, it was translated as "Spiritual Energy." It's a habit for me to say it, and everybody understands what I mean when I say it.
He is literally just spitballing strong things he knows about. He can't sense Soul King level Aizen...
Cien regained his ultimate form he had as a 0 espada, and that is weaker than base Aizen. Second fusion Aizen alone is so weak, two base Aizen tier people (Kisuke and Isshin) can't even sense his power. How would Cien possibly sense a real Mugetsu's spiritual power? Also there's the fact that he survives it...
That's why I said minimum 5-C, aka Base Aizen level. I still think 4-A can be argued through certain methods that involve, but are beyond, the sensing. It still involves Aizen, but I won't delve into it since no CRTs are planned soon anyway.
No one has a full translation of SAFWY, and you haven't read the full actual novel. The reddit dropbox version everyone has is a summary translation
Now I get what you mean. From your wording, it sounded like I watched a YouTube video summarizing it. I've been trying to find the entire novel in Japanese digitally without needing to pay, although I think I'll just have to buy it physically
. When I acquire it, I'll read it all because, first, I want to understand the story 100% with no loss in trash translations, and second, to clarify some things about the scaling.
If you think Cien is stronger than the espada because of a moment when his spiritual pressure swelled up for a bit, then you're mistaken. Read the scans in the actual profiles:
I don't use the Yammy statement for my scaling for Cien. It's ridiculous to think that 30% Cien is > than 100% Yammy and all the other Espada. However, I do believe that 100% Cien is > than Yammy, even if it's not by a massive amount.
I still argue against the idea that everything Roka copies is always weaker in some way and that her copying is limited by power level or something similar. It does happen, but unless everything I'm saying is directly contradicted in the raw Japanese, Zommari and the Cero Doble have reasons for their failure beyond Roka's power level.