Not copyright, but trademark (though it's understandable that you confused them since they're confused all the time). And from what I could glean from the United States Patent and Trademark Office's website, all the uses Nintendo applied for trademark protection were simply for the word "TRIFORCE", and not the symbol itself.
Now as for The American Academy of Actuaries you had mentioned? Their
trademark does indeed also apply to those three triangles as well, but they could only go after anyone using that symbol in conjunction with actuarial matters, not any other possible use (though I could be incorrect).
The closest match I could find to the three triangles in the "triforce configuration" in relation to video games was for
YOGATRON, but the triangles are inverted, and the trademark has been dead since 2012.
So yeah, it doesn't look like my use of the triforce symbol is my fanart is actually infringing any trademark related to video games. The funny thing about the coordinators telling me to take down the "infringing" prints was that they did so about one hour before the convention ended, so I had those prints up for 95% or so of the rest of the convention anyway, so looking back, it wasn't a great loss. But still it's pretty ridiculous whichever way you look at it.
And as for the Final Fantasy VII world map, I did some searches for a few of the more unique place names (Midgar, Junon, Gongaga, etc.), and did not get any relevant matches. So I should be in the clear with that, though I wouldn't be surprised if the coordinators raise an objection to it.
I know they're trying to protect artists from possible lawsuits and legal action, but making artists take down pieces of work for hypothetical infringement is I think going a little overboard.
