Better is to upload the files with the new name directly:
    
See https://winscp.net/eng/docs/scriptcommand_put#remarks
By using
        "put -delete -transfer=automatic *.txt *.ord" `
See https://winscp.net/eng/docs/scriptcommand_put#remarks
By using
mv you are risking renaming other files, no only those that you did upload.