I appreciate your post. I feel like there are a few people out there who got defective tracks and now everyone thinks joining track is a bad idea.
The tracks should **** together. The saw actually doesn’t care about the edge of the aluminum track. That can be off a little.

The saw actually runs on the raised part to the right of the 2 holes in the picture. Thats the feature that has to be straight.
These are extrusions so they should be dimensionally very good. The only real way to screw up a track is to have the ends cut out of square with that raised feature.
I’ve never done it but you could probably recut the ends with a chop saw.
Point is, I have old Bosch track and new Milwaukee track and both sets are better than they need to be. If you get bad track, send them back. If you have out of warranty track, try swapping them end for end. Maybe if one end is out the other is square. If both ends are out, theoretically you can fix it with a machinists square and a file.

The connectors are not supposed to force the tracks straight. You **** them hard, then tighten the grub screws.
One more thing: The tracks aren’t all identical, but they are basically interchangeable between Festool, Milwaukee, Makita and maybe Maffel. If you were worried, either buy and check and plan to make a return, or buy Festool. I don’t think there’s an enormous price difference. (The difference in tracks is the non slip strips on the bottom and the anti tip feature that many of us will never use.
Edit: Props to anyone who can correctly identify the wooden plane in the pic above. Hint, there’s a piece of scrap on the bench showing what it does and explains why I’m using it.