The seam isn't too bad and the gap is pushing the boundaries of acceptability. Those cracks are kind of the nature of the beast. At least they look somewhat natural. More worrisome is the apparent lack of silicone seal between the sink flange and the stone bottom. A translucent white or beige would make the chips at the stone bottom less conspicuous. The present gap will be a crud and mildew magnet.

See if you can slide a steak knife between the sink flange and stone bottom. If you can, there is no silicone seal. If so, the sink must be dropped, the flange siliconed, and the sink remounted until silicone squeezes from the gap. Topical silicone application at this stage is pointless and useless.

Not a fabricator, but I've bought 9 slabs of Taj Mahal for 2 kitchens, a fireplace and an outdoor kitchen. None looked like this.

I would guess your fabricator isn't using the best blades and waits too long to replace with new ones.

You also made the job harder by keeping the old backsplash.

Any issues should have been addressed before the clashing pink backsplash went in. You are only going to get a resin repair now, with zero replacement happening. And that is if this is a custom builder, and not a tract builder. A tract builder is just going to low cost muck it up with some super glue and dust. Good Taj is $150 a square and up for a reason.