The hard part is that people have already tried really hard to make and measure a superconductor in the LK-99 system, and these researchers have once again gotten close, but not succeeded. There is some precedent for this: one of the highest-temperature superconductors is two-dimensional iron selenide supported on strontium titanate, which superconducts at 100 K, while the bulk iron selenide superconductivity is a measly 8 K at normal pressure (38 K under pressure). At this point, the most plausible way that superconductivity could be occurring in the LK-99 system is if it's in a metastable or nanostructured (possibly two-dimensional) phase that doesn't like to or can't exist as a uniform bulk material.