The "date modified" should be no earlier than 8/3. I don't know about earlier versions of Windows, but Windows 10 changes both the "date created" and "date modified" to when Steam downloaded the update.
To be sure you have the current version of all the files, in your library, right-click the main CMANO game, select "Properties", and under the "Local Files" tab, click on "Verify Integrity of Game Files...". If you don't have the current version of any file, it will re-download and install them for you.
Hmmm. I did the "Verify Integrity..." bit, and it found the need to download some files, but my Pole Position files still show 7/27/2017 as before.
(I'm using Win 10 with the latest updates.)
What's interesting is that the Scenarios\LIVE folder shows an update date of 8/3/2017 (as it did before I verified integrity and downloaded anything new) even though no individual files inside are later than 7/27. (Hidden Items are shown.)