I think that I either found a bug or am unclear on intent of the TransferResult output.
Using automation along with Tom Malkewitz's WinSCP Powershell Module (https://dotps1.github.io/WinSCP/)
SFTP transfer protocol
If i try and download a file, say /remotedir/remotefile.pdf, the TransferOperationResult.IsSuccess reports True, even though the file was not downloaded to the local location. If I escape that path using the escapefilemask, which makes the new path /remotedir/remotefile[1].pdf the download works as expected and the local file is named c:\localdir\localfile.pdf as expected.