@Curious One , as I understand your post --
1. you are talking about a revocable trust for the purposes of investing/ growing
2. you are sole owner and trustee of the trust
3. You have recognized the growths every year ( what form did you file to recognize this )
4. you have used proper exchange rate to recognize the earnings.
5. The only special part here is that the trust is foreign trust ( instead of being formed under US / State laws.
6. Now you want to liquidate the trust and the questions is does this need to be reported on form 3520 or any other forms?
I am assuming that you have been reporting the foreign trust on form 3520-A as US owner of a foreign trust. If you did not then , I don;t how you recognized the earnings. Here is what I see from the IRS--> https://www.irs.gov/pub/irs-pdf/i3520a.pdf
I am also assuming that you have been filing FATCA / FBAR forms all these years -- yes ?
Is there more I can do for you ?
