While not quite what you asked I think my experience with junior devs is more illuminating than my personal experience learning React...
The most common issues I've observed amongst juniors is trying to learn everything at once. eg. React+ES6+Typescript+Redux (and probably HTML and CSS as well; and probably webpack; and Jest or some other tests... oh and the build just failed so go and debug that...).
There is just too much going on and they don't yet know which bit is which. They have to hunt through all the docs for every question they have, until they slowly piece it back together the hard way. Think of this way: if you didn't know any of these things separately, how would you know that an enum used by a JSX prop is typescript?
Juniors have a better time when they slow down just enough to learn ES6, then Typescript, then pure React (I recommend starting with React Armory for this), then add on state management. This doesn't have to be a long and arduous training regime, it's just a matter of layering things on so they know where things "come from" so to speak. The order can be mixed around a bit as well, the key thing is to learn the bits separate before putting them together.
As a sidenote to this - we provide our juniors with a specific list of key things to learn for each technology. eg. we don't say "go learn... hand-wave you know, ES6"... we say learn these specific features of ES6. Because if you don't know arrow functions you really aren't getting far! Stuff like that.