This tag stands at over 100 posts and lacks a wiki entry, but I'm unsure of how to define it. Many, if not most, of the images tagged lampion have what we would ordinarily tag as paper lantern, which would the tag redundant. Frustratingly, Google images turns up exactly the same results, leaving me to wonder what to use this tag for.
All the definitions I can find for "lampion" describe an entirely different sort of object, typically oil-burning lanterns made with glass, but sadly no pictures accompany these definitions. The closest thing I can imagine is lanterns like those in post #1143160 and post #2174052, but I have no idea how similar those objects are to historical real-world lampions or whether it would be appropriate to tag them as such.
Regardless of how the tag is to be used, there's no reason I can think of for continuing to use it interchangeably with paper lantern. Two tags shouldn't mean the same thing.