There are track lighting pendant adapters and pendants.

There is a lot going on with that ceiling with the beams and skylights. I just don’t see a good spot for one chandelier never mind three. I would stick with the current track lighting.

Spend your money on some gorgeous sconces and floor lamps to make the space more cozy at night. I agree, I’d go with just one chandelier, very airy and modern and multi tiered or dimensional if you want to fill the space or draw attention to the fireplace wall and stacked windows. I hope you go with a staircase railing that’s almost invisible. The space looks like it’s going to be beautiful.

First I'd want to know how the track lighting is currently lamped, ie., what bulbs are installed in the fixtures. From your photos, it appears the track heads have transformers which would indicate they are 9-volt heads. Those should be replaced with heads that have standard voltage. There have been significant improvements to track lighting since these were created in the last century.

Then once I find out the manufacturer of the track lighting, I'd like to know if I have options to change the light fixtures mounted to the track. Good companies have lots of options.

I'm not sure that 1 or 3 chandeliers are the right way to light your space. These seem to conflict and not complement the architecture.

I'm wondering if your solution for lighting should be more artistic in this volume of space.

I'd keep the tracks and highlight the beautiful ceiling... add the other lights you are interested in.