Right now unless you use the fix mentioned here: facebook/create-react-app#8685 (comment) you are unable to use lerna with this project if you update to react-script version 3.4.1 or later.
To solve it for --parallel --stream start commands use CI=true env. variable. This is not good for the UI of the output, but it will still work.
Let's hope they will update this later on.