How can a building project started in 2007 be fairly divided among eight partners in Syria, given the gradual deterioration of the Syrian pound's value after the war, which has affected the temporal value of the partners' contributions?

The partnership contract between you is invalid due to the ambiguity of the capital and its absence. A partnership is only permissible with present capital, as Ibn Qudamah stated: "It is not permissible for the capital of a partnership to be unknown or estimated... nor is it permissible with absent money or a debt." Therefore, the partnership is void. If you agree on the division of the building, there is no harm. Otherwise, the matter must be referred to the Sharia court or its representative, or by consulting scholars of knowledge.