I think you might be confusing something. The simulation hypothesis is rooted in the concept of the Boltzmann Braun, which is exactly what I described: A simulation of reality as in “the perceptions of a being is simulated” not “all of reality is simulated”.

I haven’t heard a single time so far by anyone seriously into that topic that a simulation would need to simulate reality to a perfect degree. That wouldn’t even really make any sense, neither from the argument, nor from the words. A simulation is always an abstraction, and since you bring up the world “simulacrum”, a simulacrum is something that by definition lacks the detail and sophistication of the original. A plastic apple is a simulacrum of a real apple, and in no way does a plastic apple replicate the cell structure or the biological details of a real apple. It’s just something that from a distance looks vaguely like the real thing.

And that’s what all forms of simulation hypothesis are based around: simulate everything necessary for the conciousness living in the simulation to believe it lives in reality.

In fact, humans have a mechanism that does just that built right into their brains: dreams. While dreaming your brain doesn’t accurately simulate reality down to the atom-level. All it does is simulate enough of your perception to make you believe you are experiencing what is happening in the dream.