How should the bank handle pending amounts resulting from international transfers that have not been withdrawn for over 3-4 years? Should they be added to the bank's profits with a guarantee, or should the bank donate them with a guarantee, or is there another opinion?

The ruling on these funds is the same as the ruling on unclaimed deposits. You must endeavor to return them to their owners by contacting them or those who sent these transfers. If you are unable to find their owners and despair of doing so, then you may give these funds in charity on their behalf. This is based on the statement of Shaykh al-Islam Ibn Taymiyyah: "All wealth whose owner is unknown, such as usurped property, borrowed items, deposits, money taken from thieves belonging to people, or abandoned property belonging to people — all of this should be given in charity and spent on the welfare of Muslims." Should their owners appear, they are given the choice: either to ratify the charity, and the reward will be theirs, or the bank will guarantee their funds to them, and the reward for the charity will be the bank's.