When I use the "Create from usage" command on a function call with a string constant surrounded by _T() and a resource ID like in IamANewFunction(IDS_SOME_CONSTANT, _T("some text")), neither parameter type is recognized.
At least _T() should hint that LPCTSTR is meant.
Resource IDs might be more difficult as they are typeless #defines, but a guess of int or UINT should be a good default type.
There is a problem with _T() as a parameter, thank you for the clear example, I have put in a bug report for this:
case=56734
I am not sure what to say about the resource ID though. Strictly speaking UnknownType seems to be the correct behaviour, at least it is a clear warning to the programmer that this is something they need to think about themselves.