I make the cut where conventional learning stops and extraordinary abilities start.
Any ruling is up to the DM, and this DM thinks it would be absurd if "learning" would extend to the inability of perception and recognition of colours, places where the simulacrum might walk where it has not seen, or the inability to follow commands because no one has commanded the original in exactly the same manner.
In basic English, "learning" means the active process of getting an understanding of something by studying it or by experience over time. So this DM thinks the best approach to defining the limitations is by looking at what the inability to learn signifies. The spell description implies:
so it never increases its level or other abilities, nor can it regain
expended spell slots.
The common factor is the acquisition of such abilities that are extraordinary and would create permanent resources in the form of these extraordinary abilities.
A simulacrum that doesn't remember commands and cannot follow them would be absurd. In the same manner, it would be absurd if it couldn't walk to places or obtain basic information about its surroundings. So this DM ruling is such that the limitations of learning concern the acquisition or replenishing of such abilities that are extraordinary and would create permanent resources in the form of abilities, feats, spell slots, traits or replenishing them once the simulacrum expends them.
Can it learn other things, such as peoples' names? Does a simulacrum
remember things that happen to it? Can it learn tactical information during combat and apply that information to make better decisions?
Based on the above ruling, the simulacrum can remember names and what happens to them. I have also ruled that they can make better decisions due to applying information that they conventionally learn, such as running a shop, haggling with customers, remembering their names and the procedures of shop upkeep.
I make the cut where conventional learning stops and extraordinary abilities start. I can also understand other DMs who would rule that some "conventional learning" might be out of scope. This ruling is enjoyable for my players - the simulacrum is a resource that my players often deploy to enrich the storytelling. Limiting the simulacrum's ability to "conventionally learn," would limit the application of the spell. Such that it would remove almost every way that my players use the simulacrum. Removing the basic functions of "learning" would render the spell defunct.