IN2MBB2PE Let me see if I can answer some of your questions.
1) The initial sentence core ends at the first comma. The "convinced that" part is technically an adverbial modifier that provides context for the main clause. However, the modifier itself contains a clause. So the basic structure is "Clause, mod (clause)": Traders have set out, convinced that limiting their investments restricted their gains.
In the second clause, "limiting" is the subject and "restricted" is the verb.
2) This kind of reasoning is a mistake. Just as in the physical world, "between" is all about your perspective. Commas are too common an occurrence for us to have consistent rules about what "between commas" means. For instance, what about this? "Impressed by her skills, the committee offered her the position, much to her delight." The part in the middle is the core of the sentence. It's not a modifier just because it happens to appear between commas.
3) We could write whole books about this, but my best advice is to start from the beginning. Identify the initial subject. Strip out text that seems to be modifying the subject or the action. Here's my process on this one in real time:
Many stock traders - this is the first noun I see, and it's right at the beginning, so it's the subject
in the United States - prepositional phrase modifying the subject
have set out - this is a verb phrase, and it's not within a modifier, so it's the main verb that goes with the subject. My core is "(Many stock) traders have set out."
to become global investors - after a verb, an infinitive ("to become") modifies the verb, showing purpose. What have traders set out to do? They've set out to become global investors.
,convinced - this *looks* like a past tense verb, but a) I'm not expecting a verb, since I already had one and haven't seen a conjunction (and/but), and b) the previous verb was in a different tense (past perfect), and c) it follows a comma. So this is a modifier for the previous action. It is VERY common for past participles like this to serve as modifiers rather than verbs.
that - After verbs and modifiers, THAT typically serves to introduce a new clause. If it were after a noun, it would make a noun modifier (e.g. "the soup that I ordered"), but here's it's telling us WHAT traders were convinced about that made them want to become global investors.
limiting their investments - "ing" words can have many uses, but since I'm starting a new clause, this must be the subject.
to the U.S. stock market - another infinitive used as a modifier. This just tells us what the investments were limited to.
, even though it is certainly home to the stocks of some of the world’s great corporations, - I am still waiting for the verb for the subject "limiting." Since this is set off with a comma, I know the main verb won't be in here/. This is a modifier, even though it contains yet ANOTHER clause ("It is home."). I can read right past this for now.
restricted - Finally, the verb for "limiting." Okay, so limiting their investments restricted something.
their gains. - this is the object for the verb "restricted." Limiting investments restricted their [investors'] gains.
4) From the above, you can see that "restricted" is a verb, not a modifier. Again, there is no rule such as "noun + comma + past participle means the participle is a modifier." The noun in question is part of a modifier that interrupts the clause, so we are just picking back up and finally getting our verb. If you are reading correctly for the core, you will be WAITING for a verb, since we are in the middle of a clause in which only the subject has been seen.
5) The "which" in D is bad to begin with. But D is also adding yet ANOTHER complication. Again, the clause we're in the middle of is "Limiting . . . restricted their gains." Now, in the middle of that clause, we're sticking a modifier to the back of "stock market" that says "which, though . . . " This sets up a contrast WITHIN the modifier. For instance, I might interrupt the simple clause "Ramen is my favorite food" with a modifier: "Ramen, which, while made from relatively common ingredients, is difficult to prepare well, is my favorite food." This does not make for a very clear or well-written sentence, but at least the contrast started with "while" is complete. We cannot use WHILE inside the modifier to contrast with the main verb, because then we are nesting the clause inside the modifier of that clause. This way lies madness!
6) Hopefully by this point, the role of "restricted" is clear. Like D, E sets up a contrast that requires more structure than we are given.
I hope this helps. This was a lot, so let me know if I can clarify anything.