Craig, what I have found over the course of the years is that they do have a tendency to warp if they are out in direct sunlight. The ones in the shade, not so much.
If the warpage isn’t too bad I can usually hit the warped spot with a dremel and all is good (for a while).
I have replaced a couple with metal (aluminum) frogs that I fabricated myself.
There was one type of frog that I was casting that wasn’t very prototypical looking. It looked like a piece of 1/4" thick square plastic with a V-groove in it. They’ve proven to be very reliable and no warpage. But like I said, not very prototypical looking.
If you want I could get a couple a pictures to show you what I mean.
Now, there may be some resin casting material out there that is UV protected. I just haven’t looked for it.
The points are just rail ground down on a grinder.