Did anyone actually read the Tzemach Tzedek in question? He writes he heard about this refuah, and calls it a refuah she’eina badukah. IE, he has no clue about it, and allows it due to lack of more information. If he knew its source he wouldn’t allow it at all.
(unless you believe the Tzemach Tzedek is the nasi hador and is infallible, but that’s for another thread).