I know what you mean, Nooka; ds has also not been a confident reader. But two things still spring to mind:
*his difficulties are personal to him- some unknown censor isn't going to know what he, as an individual, finds difficult.
When I was a child, received wisdom was that what made books easier were large print, first person narrative and the present tense. Now these happened to be precisely the things that made books more difficult to understand for me. So "easier" books were more difficult iyswim. I'd have done fine with Harry Potter, but would have found Michael Morpurgo more uphill going.
*not all children are easily discouraged by difficulties. If you set out saying that all children should have parents/teachers/censors make sure they are not doing anything too difficult, then you are not helping the type of child that thrives on a challenge.
Some children, oddly enough, get on better with more difficult work. My parents were right to let me have a go at reading the Oddyssey in the original with a wordlist at the age of 9, despite my having no knowledge of the language. Of course it wasn't actually possible (ancient Greek doesn't work like that!), but I was enjoying myself, I was excited by the difficulty of the task and some of that thrill stayed with me when, years later, I actually set about learning ancient Greek in a more conventional manner. Early failure did me no harm at all.
As for my English, I am largely self-taught. I started dragging a dictionary round at the age of 7 or thereabouts. Should my parents have stopped that, just because I might have got discouraged?
I am sure you are doing the right thing for your children. But this wouldn't necessarily be right for mine. Or at least not for both of them. Children are individuals.