Mag it's the shortcut for May in italian, it's something that does automatically the italian version of Dreamweaver (which is used to create that page) when set a "date" field on a web page. Never noticed it before...
It should not be difficult to find out when the full GSX installer was last updated.
It's not difficult, because it's not required.
Since June 2016, when we released the new Live Update, you don't really need the full installer anymore, since all full installers run Live Update at the end (so they will always get the latest files automatically when they are run), and you can run Live Update manually, and Live Update WILL notify you of updates, when they come.
but is it such a difficult thing to keep the current product version or at least the correct date the product version was updated on the product page?
It would be wrong to do that. That's only the date when the *full* installer was updated and it IS correct, and it's not really useful to know since, as I've said, whenever you run it, it will download something which is already newer than date. The only users that might be interested in that date are those that either:
1) Have a very old version of the full installer, one that doesn't use the new Live Update
OR
2) Need to install without an internet connection, so the Live Update which is run at the end will not do anything, so it might be useful for them knowing what they are going to get.
If we followed your suggestion, and updated that date to show when the *product* was last updated, even with a small file that came with Live Update, users would be mislead into needlessly downloading the full installer again, just to get the same files they would get anyway, because the installer runs the Live Update at the end. So, the date is correct as it is, because it tells when the full installer was updated last, which might be useful to know for someone installing offline, so he will know that he won't get the very latest fixes.
Live update gives no confirmation of anything when it is complete, it abruptly and quietly quits. It would be nice if it could tell us what version (of what) we have been updated to.
It always update the latest version of EVERY file of EVERY product. So, a version "number", would be meaningless, because individual files of all our products might have been updated way past their installer release version. Not that this matters, as long as you install with a working internet connection.
So no, what you REALLY need to read, are the Live Update RELEASE NOTES, which can be read from the Live Update menu inside the sim. This will tell you exactly the dates where things were updated last, and you can be sure that, by running the Live Update, you'll get all these additions, regardless of the version you installed, provided it's a rather recent installer, one that comes with the new Live Update, which means something release after June 2016.