I see from your GitHub project that you use scipy.optimize.differential_evolution. I have used scipy's Differential Evolution genetic algorithm to determine initial parameters for fitting a double Lorentzian peak equation to Raman spectroscopy data and found that the results were excellent. The GitHub project, with a test spectroscopy data file, is:
https://github.com/zunzun/RamanSpectroscopyFit
If you have any questions, please let me know. My background is in nuclear engineering and industrial radiation physics, and I love Python so I will be glad to help.
James Phillips