usually, high speed signal are organized in differential pairs, and these pair groups are in (approx.) same length. So "squiggly traces" is a method to guarantee the length.
You can find them in most high speed designs, maybe on your motherboard or GPU cards.
I take it each of those pairs of lines is connected to an associated pair of differential pins on one of the FPGAs then? That sounds like it could make the boards rather more versatile.