Is there any way to use chatgpt to improve fet results ?
You mean for the algorithm? No.
Or do you mean ChatGPT should help to use the FET (So the GUI, interface, how to add constraints, ...)? I didn't tried. If ChatGPT read the manual and the forum (that might be done) it might have learned how to use FET. I didn't tried it. But i am sure you will get better support by the forum and not by ChatGPT. Maybe try it and report your results.