'Mysticism' means "immediate spiritual intuition of truths believed to transcend ordinary understanding" or "direct, intimate union of the soul with God through contemplation and love." (See first post, NOTES.)
Are you saying that Yogananda did not teach this?
I think Yogananda did teach this sort of thing, ostensibly as a "science"; but the important point was that Burbank, by his own words in a testimonial used by Yogananda, disdains mysticism.
Although I didn't allege any reporting error in re the Yogoda teachings, you yourself said that Yogananda "downplayed" the mystical elements to gain acceptance in the West.
Side note: Calling something "science" does not make it a science. Granted, the contours of "real" science are fuzzy, and it's not always easy to distinguish good from bad (or non-) science. But it usally is - as I think it is in this case.