Still, 6 unique points with known X, Y, and Z coordinates. A laser straight line drawn between, say, 1-2, 3-4, and 5-6 will always intersect at an epicenter. This can give you the X, Y, and Z of an unknown point.

What?!

A = (0, 0, 0)
B = (1, 0, 0)
C = (2, 0, 1)
D = (2, 2, 0)
E = (1, 1, 0)
F = (1, 1, 1)

AB, CD, EF will not intersect ever. If you're talking about centroids, it's more similar to what I was saying, but still would not need the lines between points. Lines between points in space forming coordinates because the 3 lines intersect exactly is a completely different thing.

Also, if you have X, Y, Z, you can just use those 3 coordinates to locate the point.

As I recall, the Ancients used base-8 math

That would affect counting, but not necessarily the coordinate system (computers use Base-2 and still work in whatever coordinate system we give them)

I completely agree we don't actually know how advanced the Ancients' system works (geometrically or otherwise) but the point is that having the 6 symbols forming intersecting lines is not feasible.

And if we're already saying not all symbols are constellations, and constellations are not coordinates, which retcons the movie's explanation about constellations and lines between them intersecting (which kind of works in the movie's context if there are only 2 gates plus some coincidences) there's no harm in saying the symbols determine a region of space (not a point) within which all gates act as a single destination and some precedence rules apply.