Post History

The problem with your names is not that they fail to be distinct, but that they fail to be sticky. The stickiness of a name is a measure of how easily the brain can retain it and assign it to an object. If names are not sticky, making them more distinct will not help the brain retain them. The reader's confusion is not based on the distinctiveness of the names, even if they are reporting them that way, it in the lack of stickiness. The names just hasn't stuck yet, and that is why the reader can't keep them straight.

This is a cultural problem. It has been observed many times by English readers of Russian novels. Thoss long Russian names, usually with patronymics attached, are highly distinct, but they are unfamiliar and so we have trouble retaining them and assigning them to objects. They are not sticky for an English reader. Thus we get lost and can't remember who is who. 

I have exactly the same problem in my Anglo-Saxon novels. There are a few Anglo-Saxon names that have come down to us and are still familiar to us today. I tried to use only those familiar names for my characters, and for the first few drafts, no one objected to them. But then an agent who is considering the book said that the names did not sound authentic enough. So I changed them to less familiar but still distinct and easy to pronounce names. Did it sound more authentic? Yes. But the first thing that the first beta reader for this version complained about was that it was hard to keep track of the names. Authentic, yes. Sticky, no. 

I don't think there is any way to make names more sticky without making them more familiar. All I can think to do is to introduce them more slowly. Delay the introduction of some characters as long as you can so that the reader only has to remember a couple of names. Less sticky names will take longer to fix themselves in the reader's mind. 

Also, add a Dramatis Personae so people can look the names up if they don't remember. There is a reason you see this in fantasy books and historicals more often than mainstream books. The names are less sticky.