If the term being used is "bardo" or a Chinese phonetic version thereof, the source is quite definitely Tibetan. Tibetan Buddhism has grown astronomically in Taiwan in the past few decades, but the phenomenon has not been much studied. A recent collection that begins to rectify this may be found here: https://publications.efeo.fr/en/livres/913_the-hybridity-of-buddhism
As it has not yet been mentioned, I dare to add that in regard to this concept in East Asia (though not for the most modern periods, and therefore not directly relevant to the query), one should certainly see the article "Chūu" in the fifth volume of the Hobogirin (5: 558-663).
Dear Dr. Yamamoto,
Hi Carl. The bardo is not a Taiwanese nor Tibetan invention. There is elaborate debate about the concept (Skt. antarābhava) at least back to the 2nd century BCE Kathāvatthu. There is a good link about it from UVA with references here: https://collab.its.virginia.edu/wiki/renaissanceold/Concept%20Encyclopedia%20Analysis%20-%20The%20Bardo.html.