Interesting question. My instinct is that the collective reading is by far the more natural one. I do agree that the availability of the singular “they” makes the distributive reading more plausible. Yet I wouldn’t totally rule out the distributive even in the “we” case. There are a couple more factors at play:

One, to “tell each other” often has a positive, reassuring connotation, which supports the collective.

Two, to [verb] each other seems to have ambiguous timing embedded in it somehow. Compare “we passed each other on the street” [simultaneously] to “we wrote each other” [sequentially]. If we assume the simultaneous timing, then your examples lend themselves to the collective reading. If we assume the sequential timing, then your examples take on the distributive reading (even in the we case).

Interesting question. My instinct is that the collective reading is by far the more natural one. I do agree that the availability of the singular “they” makes the distributive reading more plausible than it would otherwise be. Yet I wouldn’t totally rule out the distributive even in the “we” case. There are a couple more factors at play:

One, to “tell each other” often has a positive, reassuring connotation, which supports the collective.

Two, to [verb] each other seems to have ambiguous timing embedded in it somehow. Compare “we passed each other on the street” [simultaneously] to “we wrote each other” [sequentially]. If we assume the simultaneous timing, then your examples lend themselves to the collective reading. If we assume the sequential timing, then your examples take on the distributive reading (even in the we case).