Engage, as it were, in close quarters...
To me, this means He did not observe as a prison guard, but rather felt and was subject to the horrors of hell.
Engage is active participation, while close quarters is combative and implies Christ was subjected to torment.
It’s not a notion that is acceptable at all.
You are over-parsing words to prove a point that can not be proven. We can not ask Calvin exactly what he meant so we can argue indefinitely about what we THINK he meant. That is pretty pointless.