Um, not to put too sharp a point on it (pun intended), but "square" point wood ("prongs) only applies if your groove is ALSO square. I have a number of V-groovers that are custom ground to angles other than 90*, with corresponding jigs allowing me to machine matching angles on the prong pieces.
Even on traditional 4-point cues, "square" (that is, a perfect 90* angle) is not the most important issue; perfectly matched angles between the groover and the prong piece is what matters. I know one very highly regarded cuemaker whose V-groover was factory mis-ground to about 92*. Appropriately, this guy built all their other jigs and tooling around that angle, and continue to put out perfect, air-tight points to this day. The groover is sharpened "in house", and replacement groovers (every few years) are ground to match that original 92*.
My advice is to start with a groover you can reliably replace (or have sharpened) when it dulls. If it's a perfect 90* - the best-case scenario - then you did great. However, if it's off angle a little bit, just experiment with the rest of the system until you get a perfect [repeatable] fit.
TW