I see no glaring errors from those pictures. Looks good to me.

Looks typical as in okay.

I’d be more concerned about having that plastic filled quartz behind a range and cooking surface. The heat can most definitely scorch your backsplash.

Caesterstone Ai agent:

Q: "Should a gap be left between a quartz countertop and a quartz backsplash to allow for movement?"

A: "Yes, it is recommended to leave a small gap between the quartz countertop and the quartz backsplash to allow for movement and expansion. This gap can be filled with a flexible sealant, such as silicone, to accommodate any slight shifts and prevent cracking."

Copilot Ai:

Q: "What materials should be used at the junction of a quartz countertop and quartz backsplash?"

A: "Use a flexible, waterproof sealant — not grout — at the junction of a quartz countertop and a quartz backsplash. This joint is treated as a movement joint, because both the countertop and the backsplash expand and contract slightly with temperature and humidity.

"How the joint should be built

• Leave a ⅛" to ¼" gap between countertop and backsplash.
• Fill the entire gap with silicone (not just surface‑level).
• Tool the bead smooth so water sheds downward."

I don't see the issue and sure hope not behind the range

Sales guys say quartz is 93% stone, That's by weight. Which doesn't matter. The amount by volume is 65%. The 35% is meltable plastic resin. It has to be protected.

Nothing you mention is an issue. At all. The issue will be the scorch generated by the heat of the range.

There's nothing wrong with your silicone job.