Extra post for happy news (and shameless self promotion)! All treasure maps found!
Thank you all here in the forums for helping me find the last missing maps 
Part 1 (maps V, XI, XII, XV, XVII): https://www.youtube.com/watch?v=ppkeaYekcTg
Part 2 (maps II, III, IV, XVI, XXII): https://www.youtube.com/watch?v=AwOqGvgSAw0
Part 3 (maps I, VI, X, XVIII, XXIV): https://www.youtube.com/watch?v=4UEMsZwuC30
Part 4 (maps IX, XIII, XIV, XIX, XXI): https://www.youtube.com/watch?v=7byIU63vcpk
Part 5 (maps VII, VIII, XX, XXIII, XXV): https://www.youtube.com/watch?v=MlYlLU3977U