Not a definitive answer, but one to make others with experience to look at these pictures again.
Its easy to miss picture 5, when the first four show good looking Night Herons (from an european point of view).
On Germany, there is an old childrens play (heißt es Dachgiebel oder Dachgabel? ....) or in other words: what the first bird? A Night Heron. Whats the second bird? A NH. Whats the third bird? A NH ... Its hard to avoid it, but you can, just try it.
This isnt meant as an offense! Also to eberack, normally (99%) its good to post several individuals of what you think its the same species in one thread, but I think this thread is the rare 1%.
Just look at picture 5 (and forget the others): is it a Night Heron? No, because:
strange bittern like striping on neck and upper breast
yellow in supercilium
strange head pattern consisting of horizontal stripes.
But what is it?
Is there another ssp or form of Black-Crowned NH in Namibia?
I have seen many NH in Europe, so I am quite sure this is out of variation for this species. But happy to learn
A quick look at the Collimns Guide shows a Striated Heron