When : 1. time marker / 2. and it was the moment

Question

I had just arrived at the hotel when I remembered that I had left my keys in the office.

Here, when means "and it was the moment that~", so it means,

I had just arrived at the hotel and it was the moment that I remembered that I had left my keys in the office.

But how about this?

I had gotten used to coffee when I was in Brazil.

Here, when means during, which is just a time marker letting us know when the main clause happened. So, this means,

I had gotten used to coffee during in Brazil.

So, here when means two different things:

1: and it was the moment that

2: during(time marker)

So, I'd like to know what's going on here with the conjunction when.

Answer 1

Context, context, context! . . . No word means anything outside of its context.

When doesn't really have two "meanings" in your sentences, but an overriding sense of something like at the time that. The contrast you observe, between a duration and a point in time, is imposed by the context—specifically, the aspect of the verb involved.

• Remember in remembered that I had left my keys is "punctual"—an event which occurs at a point in time, so here when refers to that point.

• Was in I was in Brazil is "durational"—a state which endures over a period of time, so here when refers to that duration.

Note, by the way, that verbal aspect is also context-dependent: tense, aspect and modality are really properties of utterances, not words, and we select different verb forms and constructions to reflect ("agree with") the underlying situation spoken of.