Both stories can be read on this very site.
[
eldritchdark.com]
[
eldritchdark.com]
Haunted Gong comes with a note from CAS' friend Dr. Farmer, so it's more than likely CAS wrote it. And both stories very clearly have his style, but they're notably weaker than most of his work.
I can't say when exactly they were written, but I'm going to assume, from the subject of the book they were published in, that they're among CAS' oriental juvenilia.