That mini series is indeed a great watch but it's also not exactly factual.

Are there inaccuracies around the portrayal of why and how the reactor failed?

I don’t think there are fundamental inaccuracies about that, but there are many exaggerations about the immediate aftermath. E.g. the fireman’s hand burning from touching a graphite fragment stood out as a particularly egregious one. And it is in fact shown that the disaster was caused by incompetence and carelessness, which does support GGPs point.

Flaws? The meltdown was caused by a deliberate action on behalf of people with control of the plant.

I haven't watched Chernobyl because I prefer to not get my history from television shows with a narrative axe to grind.

My understanding is that those actions were only capable of causing the problems they did because of specific design choices involved in the coolant and moderation systems. Is that wrong?

That's not wrong so much as it is a disingenous way of looking at the problem. It's like saying the Titanic only sank because there was no system that prevented them from sailing it into an iceberg; I mean, alright, sort-of true, but sort of a "missing the forest for the trees" sort of take, isn't it?

Not really. We understand a lot more about human error now than we ever have, and we design for it. A design which allows for human failure and fails safe is less good than one which does not. It would have been possible at the time to design out those failure modes. Does that not make it reasonable to talk about a flawed design?

I don't know if this bit is true, but specific reference is made in the show to the displacer rods being made of graphite because it was cheaper than an alternative material, which caused a problem because they acted as an accelerant rather than a moderator when the cooling rods were partially inserted. Fine as long as the control rods don't get stuck, or get pushed out by evaporating steam. Again (if true) that's a design choice which made the situation worse than it might otherwise have been. Is that not a flaw?