Is the Kaloterna collection fictional?

Egyptian mummy mask
reported to have formed part of
"the Kaloterna collection"

Just over a month ago I raised some questions about the Kaloterna collection. Nobody has pointed me in the direction of other objects from this collection. Could this collection be fictional?

What is the authenticated evidence that Zuzi Jelinek acquired this mask from the Kaloterna collection? Did this take place in the early 1960s? Where was Jelinek living when the acquisition was made? Does Jelinek have any (up to now overlooked) record among her papers?

If the Kaloterna collection did not exist, where does it leave the due diligence research by curatorial staff at the St Louis Art Museum? Would it mean that the mask was acquired "improperly" (to borrow a word from SLAM's Director)?