Hello Pulpmeister,
All of what you say is true, yet I do not think it is safe to assume that everything written by HBJ will be public domain in the USA.
The publisher linked below has been adding HBJ titles even in recent months; I'm not sure they would have gone to all that effort if it was all about to tumble into the public domain.
At any rate, they are a fine small press; both their paper and ebooks are good quality.
https://steegerbooks.com/shop/the-sphinx-emerald/
As for Bedford-Jones himself, I've never been disappointed reading his stuff!