1. Congratulations on doing research and being such a conscientious student of the language.
2. I have a few comments. These are not answers. Only the teachers can give "answers." If a teacher disagrees with
my comments, you must accept the teacher's.
3. To the best of my knowledge, "be intimate in" is not an idiom.
4. Let's forget "often" for a second.
5. The sentence is: Those meetings + were + intimate (in nature):
Those meetings = subject.
were = linking verb.
intimate in nature = the adjective phrase that describes "those meetings." ("Those intimate meetings.")
6. Now let's add "often." I believe that most high school teachers would simply say that it is an adverb
that modifies "were."
7. According to most books, an adverb of frequency comes after a form of "to be."
a. Thus: "Those meetings were often intimate in nature."
8. Since languages were invented by human beings, there are -- of course -- exceptions to the rule. If you wish
to emphasize the verb for some reason, you can then place the adverb of frequency in front of the verb -- as did the
a. Thus: Those meetings often were [the word "were" is pronounced strongly] intimate in nature.
i. I do not know why the author wanted to emphasize the verb. Maybe some people believed that the meetings were
not intimate in nature, and the author wanted to say that they often were. / Or maybe the author made a "mistake."
That is, maybe he should have placed it after "were."