Hello,
these shell columns dont have a title (in any language!?) and dont appear inside "Preferences / File Display Columns / Appearance" and context menu columns list.
Directory Opus 13.14.9 (Beta) Build 9232 x64
OS 10.0 (B:26100 P:2 T:1) SP 0.0
Only the Seiten column (System.Document.PageCount) is available, but it is not selected from Preferences / File Display Columns / Shell Properties.