If you can keep the ties completely fixed and only the rails move, you will either get big gaps or kinks, or both.
Pretty hard to fight the laws of physics.
Adding gaps was a good idea, but why butt the rails and then cut gaps? I guess the "nails" around the gaps are really tie spikes? I think you will find that over time, if you cut gaps on curves, the nails won't maintain a smooth curve at the gap.
One thing I've seen over the years is the progression of "thought". In the early days people bolted everything down to keep anything from moving. Normally if the ties were solidly fixed, the rails began to rip out of the ties.
The next "school of thought" was that ok, fix the ties, but let the rails slide. Well, the specter of physics rears it's head again, as while it seems to make sense, the issue is that the friction of the rails in the ties is not consistent (for many reasons), and you are back to big gaps in places and kinks in other areas.
Finally, the evolution has come to most that you loosely locate the ties, and let things move like the real trains do. Many people will try to argue that our scale does not work like the 1:1: but it does.
If you look at the prototype, they go to the effort to do the complete opposite of letting the rails slide in the ties, and lock the rails to the ties.
One of the big issues we have is the radically different expansion of the rails vs. the ties. By locking them together at multiple points, then the ballast is the thing controlling the movement of the track, again like the real thing.
Anyway, you have 3 different expansion coefficients going on now, the rails, the ties and the boards. Your temperatures might be mild enough that virtually anything works, but a good inspection at the temperature extremes is what will tell.
In any case, your workmanship is superb so if anyone has the chance of success, you will. (But I still would recommend SplitJaws at your gaps)