Cilician gates are in the mountains.
Macedonia is a mountainous country which makes the Macedonians natural experts in the mountainous warfare.
Alexander just left the Balkans where he brilliantly defeated his enemies in the extremely mountainous arrears.
In OTL during the conquest of the Persian Empire Alexander used to astonish the locals by the Macedonian excellence while campaigning in the mountains.
So, my guess, the Macedonians would have come up with some solution to this "Cilician gates problem".
Macedonia is a mountainous country which makes the Macedonians natural experts in the mountainous warfare.
Alexander just left the Balkans where he brilliantly defeated his enemies in the extremely mountainous arrears.
In OTL during the conquest of the Persian Empire Alexander used to astonish the locals by the Macedonian excellence while campaigning in the mountains.
So, my guess, the Macedonians would have come up with some solution to this "Cilician gates problem".