Fluorescent lights have a spectrum significantly different from sunlight and/or incandescent light. Wall paints are composed in a manner where they maintain their visuals pretty well.

Art paints, however, contain very vivid pigments that have narrow spectral responses. An incandescent light source produces a continuous spectrum (like sunlight does) and will catch those narrow spectral regions. The spectral composition of fluorescent lights, however, is mixture of line spectres and fill-ins. It may appear identical to the human vision but not so to the very narrow-minded painter pigments.

You can check this visually if you have a prism of suitable material for creating a rainbow on paper. With an incandescent light source, the resulting rainbow will be continous. Fluorescent lights will tend to produce significant banding.

My advice would be to try sunlight and see whether this makes a significant difference. Another option for testing is to try a flash (a UV suppressing filter for the flash might be worth a try of you fear for long-term color stability, but then it doesn't sound like you'd be doing this for days on end).

If either makes a significant difference after color calibration, there might be a point in trying to get a hold of incandescent light bulbs, possibly halogenous ones (they burn hotter and thus are a bit more similar to bright sunlight).

Or check your paint supplies for other options: it's not like one can avoid fluorescent and/or LED lighting in future, so some paints might be more suited for indoor exhibitions than others.