it seems to me that when they are unrealized gain/loss for open payable or open receivable you have the details with the type (journal, Bill, invoice, etc.) and the source currency. On the other hand, if you talk about the revaluation for the other accounts, in fact we do not have the details. The only way to have it is to customize a balance sheet and filter on the account in question which has been revalued and add a filter linked to the currency.