This encyphered engineering book is interesting, maybe?

[Bernd]

Ghiberti copies a lot of designs from Kyeser and Vegetius, just like Taccola. But he has a much better grasp on perspective

I can't tell who is the better artist, but neither of them understood what they were drawing. 

Those are supposed to be well-known devices for lifting water (You are not allowed to view links. Register or Login to view. and a You are not allowed to view links. Register or Login to view. or You are not allowed to view links. Register or Login to view.; but their shapes, placement relative to the water bodies, and the flow of water are all utterly wrong.

Are those images from original manuscripts by Ghiberti, Taccola, etc?  Or from copies thereof, made by mindless scribes?

Taccola made much more mistakes regarding perspective that Ghiberti. And you are right, most of the drawings don't make any sense, but that's not a problem - just like in herbals. I've made a thread about Vegetius (the source of all the military literature) and the implications here:
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The question is - who invented those (often nonsensical) illustrations? The original work is from Vegetius but it was not illustrated. The earliest illustrations are vom Konrad Kyeser's 'Bellifortis', followed by Taccola. My guess is the war machines came from Kyeser while the water lifting devices are from Taccola. But I am far from certain. It's complicated since the illustrations in manuscripts and later printed editions appear to have copied from each other.