I'm not sure it can be fully interpreted as that. That just really says that she had 9 Yin Chi. "real key" is a single unit here and isn't a reference to whether it's true or complete 9 Yin chi. 9 Yin Shortcut chi is still 9 Yin Chi, just not all of it.
In the interest of melding it all though, we could say that the 9 Yin shortcut only has the yin portion. Or rather, I'm being led to believe now, the portion that ZZR had to practice was yin. This does make more sense since you're right about the shortcut portion being technique now that I think about it.