Previously

Previously
 

Based on

p.66 [...] prepares to deliver her summation as she has seen it done many years previously by [...]

, could I use have been? (not were)

-The exams that __ distributed to them last week [...]

There's nothing in the first sentence that sounds odd. It is using the perfect tense correctly, and would mean something different if the past tense were used instead.

Your question about using 'have been distributed' sounds strange to my AmE ears. It may sound better to someone with BrE ears.

Is it owing to the existence of last week?

Yes.

Thanks.
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You say
-p.66 [...] prepares to deliver her summation as she has seen it done many years previously by [...]

would have a different meaning if 'has seen' is replaced by 'saw'; what would be the difference? I would have said 'has seen' is wrong, because you are talking a long time ago (=many years previously), then only 'saw' is correct, and 'has seen' should be wrong. But of course I trust you are the correct one, and I am just looking for a better explanation, though it might not exist.

It is a game of reference. If what was done in the past is not being referenced as if it still applies to this day, the past tense is used. Otherwise, we use the past perfect.

So, 'as she saw it done many years previously' implies that she no longer sees it (it only happened many years ago). But 'as she has seen it done ...' implies that she still sees it being done. The "many years previously" phrasing kind of makes it seem wrong at first glance, but we're ignoring how long ago something happened. It is the point of reference that matters whether the past tense or the past perfect is used.

Excellent answer. Thank you.