Question to your first statement: I’m running some some Kontakt libraries in addition to HALion and NP. When I change tuning in Playback Options to 442, the change automatically happens in Kontakt as well? Nothing needs to be changed in these other libraries?
oh (dear), that’s really low for a beautiful old Blüthner piano. How does it sound that way? I would try to get it up to 435Hz…
I had an old ca. 1900 piano „Eccles London“ that could not hold the pitch. My piano tuner, who was a kind if a freak, lay the piano onto its back (with a special construction he had built) and injected some magic tincture into all peg holes. Since then the instrument is up to pitch - since over 20 years now.
It’s a 6’3" model 7 grand c. 1895, with the Bluthner patent action. I understand it suffered a lot of water damage during a house fire some 40yrs ago, which probably explains its pitch problems. That said, it sounds beautiful - warm bass and middle, with a bell like top range and a light, responsive action.