It's one thing to say that constellations of stars don't exist. It's another thing to say that the constellation "Leo" doesn't exist because it isn't a lion and our perception of the spatial relationship of those stars has nothing to do with lions, or with mystical astrological significance.

Those stars are present in space in a certain way. And we can perceive them in our sky in a certain way. But whether those stars are "connected" in any meaningful way, or whether they contain any inherent Lion relevance is purely a creation of human imagination derived from real observable objective phenomena. We could just as easily have said that Leo was Orion, and Orion was Leo, and have been equally correct. It's subjective. Which doesn't mean it's meaningless for us, otherwise art would be meaningless. But it does mean that it isn't "real" in the same way that gravity or the sun are real. Anything whose continued existence is conditioned on belief isn't "real" in an objective sense.

Belief can certainly will unreal things into meaningful reality though. But, absent that belief, those things will not exist.

Really this is a discussion centered around the inadequacy of the English word "real." Perhaps other languages have specific words that would more clearly demonstrate this distinction. Because clearly gravity and Pisces are not both "real" in the same way. The former is objectively real and the latter is subjectively real. And we're talking past each other by not simply having seperate words that distinguish between those concepts