To read meaningfully, one needs to be able to not only decode and pronounce a word, but also know what the word means and understand what is being read. And these skills must be applied consistently and not consistently inconsistent.
Do watch out for the illusion that your child is reading when in fact, he/she cannot recall facts accurately and/or presents a varied (not necessarily different) version of what was read.
You can cross check by asking the child, “what did you understand about the passage?” or “tell me/explain to me what you just read”, instead of “do you understand?”. A closed-ended question may not draw out the issues.