Why not transfer the file to a USB stick and erase it from your HD to gain back the space, then worry about what it may be later. This would also tell you if the file affects anything if removed from the resident HD.
I suppose I could do that, though then I'd be afraid of forgetting about it! LOL...
On my laptop, I'm not sure how I'd notice if it affected anything if removed unless it was a really obvious. Any idea what could be affected? ...maybe that's a silly question?
Nope, no idea, but since I began using Macs back in 1988, I have experienced plenty of weird things that I just gave up and trashed.
If you're worried about it, just label the stick and set it on your desk, then use your reminder to set a prod for 30 days later. If you haven't missed anything or had any further issues with your Mac, do whatever you wish with the file, but you will then know whatever it is no big deal.