Wintrust
Wintrust is being worked on by PaulVriens and JuanLang.
WinVerifyTrust
Wintrust.dll is where WinVerifyTrust is implemented. It's partially implemented in Wine, but doesn't bring up a GUI in cases when it should. It also isn't implemented for every possible action ID, and may cause crashes due to unimplemented functions.
Catalog files
The catalog functions in wintrust are incomplete. At least a few apps need more a more complete implementation of them:
CryptCATOpen attempts to get the attribute cert portions of the catalog file, which is a CMS signed message containing a CTL. Attribute certs are unimplemented in Crypt32, so this is essentially dead code at the moment.