The harbor, as KT, is way more tanky than a normal dock, and you do need way more spearmen to take it down in time.

Counter dock in KT is generally just a terrible idea. The extra hit points make it so difficult to fight into them.

Knights Templar actually needs gold to produce a keep as well.

I think in some situations it might also just be worth if you're both going for dark age spearman to just ignore water for the dark age and just try and get an age up in first and then go for water afterwards. I think it's more beneficial for Knights Templar rather than Mongols because they of course also get access to the pilgrims and they don't have to idle any villagers during the age up. They can't make villagers but they don't have to idle any.

Against the Knights Templar, Mangudai are actually a pretty good response because you're playing a civilization that likes to be out on the map chopping wood. The wood line gets thinned pretty well there.