Turns out I'm the idiot here, for some reason when I went to put the files back into the RDR2 folder the "LennysSimpleTrainer" folder with the .dll was not there. My bad! 😧
Also one thing that concerns me is I accidentally loaded into Online which was the reason I took the trainer out and it did not auto kick me off the game, it let me open the trainer menu and I hit Alt+F4 so damn fast before it was detected.
Also having the same issue and I'm not in the epilogue yet, just need to wait for them to update it I guess. Pretty sure another trainer on the site is also crashing so it's not just Lenny's Simple Trainer.