Fluorescent lighting can be corrected - to a point ... not completely.

The spectra of ALL fluorescent lighting is "bumpy"; not really a smooth curve as would be the result of "black body radiation", and the dichroic correction in the enlarger will be smooth. Add to that the vagaries of the film emulsion in response to the bumpiness and the problem is even greater.

The images can be improved. I've found that it takes a lot of effort - something that would place the printing well into the "custom" area. A FLD filter - I've used them - will HELP, but IMHO will not be a panacea. If I have no other choice but to photograph under fluorescent lighting, I would most certainly use the FLD.