Is that back piece level? It could be be optical illusion, but it looks like the piece dips in at the faucet hole. You might want to take a level and place it parallel to the sink over the faucet hole.

The seam isn't bad, however, the 90* corners in your sink cut out have voided your quartz warranty. I'm not fond of the negative sink reveal and they didn't even knock the meanness off the bottom edge. With normal sink activity, that's a chip factory as built; you've already got one at your seam. This is why I always do a slight positive reveal on all my sink replacements; the bottom edge fits tight against the sink flange and is protected.

The top "pencil edge" sink profile isn't my favorite either. It's gonna chip and should be more rounded no matter what your designers says.

And if I may be so bold, you've got an apparently fat front sink rail. What is that thing 6"? I'd have made it half that.

chispa's suggestion is excellent; picture with a straightedge please.

I'd usually recommend an apron sink replacement to fix these and the seam problem, however, it appears you have full-height doors with no drawer, probably precluding that solution.

This is the proper bottom edge treatment of a negative reveal.