Is this Excel spreadsheet altered?

It isn't clear what you're asking.

Altered from what?

What does this data represent?

From the file name, it's not even an 'Excel spreadsheet', it's a plain-text, CSV file that you've opened in Excel. CSV is about as basic as you can get, so there's no concept of file versioning, activity tracking, or anything similar. My guess is that's simply the last modified timestamp of the file. As to who changed it, there's absolutely no way anyone here can answer that. We don't even know what the file is, where it came from, or who might (or might not) have access to it.

I will say that Apple, generally, are not in the habit of changing users' files, but without context there's nothing more that can be said.

No Apple employees participate in these user-supported, public communities. How could we possibly know the answer to your question with the current information shown?