Is it necessary to end the sentence after "of which", "to which", etc. with the word linked to proposition?
Solution 1:
All of those sentences are correct, although not in a form you would commonly encounter.
When you see "of which," it is typically designed to rephrase a sentence so that it doesn't end with a preposition. It's a myth that ending a sentence with a preposition is wrong, but it is still avoided by some people. (Even if somebody doesn't believe it to be wrong, they might prefer the alternate writing style.)
- Original: These are the spiders she's afraid of.
- Reprhased: These are the spiders of which she's afraid.
The sentence examples you give have a similar quality, but are more complex. Interestingly, it's the use of the commas that seems to result in any awkwardness. (And, perhaps, some verbiage after as a result.)
If you're worried about how they might sound but don't want to change them into two sentences, you could replace the commas with em dashes, along with some other rephrasing. (Incidentally, doing this also removes your use of "of which.")
- She discovered so many spiders---her greatest fear.
- He answered all the listening and reading exercises---as he had predicted, the test had consisted mostly of those.
- The team won a silver medal---a proud recognition of their hard work..
I may have changed things too much, but the idea is there. I, however, don't necessarily have an issue with the original construction. Depending on context, it's a more simplistic phrasing. Changing them as I did---or turning them into two sentences---will also change their tone of voice and "reception." You will need to determine what your priorities are.