I see. The save slider value issue likely stems from the float.ToString() and float.Parse() functions now being conflated with different regional formatting if your prior save was on a different region.
Similar functions are used to process model data, which the modpackassets folder and modpackmodels folder uniquely contain.
I should be able to modify my code to be more portable across different regions, I erroneously assumed some of these functions by default did not utilize regional formatting.
Also, huge thanks for uncovering these errors. They would have remained unrecognized otherwise.