Angularjs to angular4 to angularjs
I've been into this process before ( immigrating from angluarjs to angular ).I strongly recommend you to just rewrite all your component in angular 6 again ( there is some basic changes from angular 4 to 6 too )It will less time than this method.you can keep your html and css with minimum changes.
anyway if you still insist in your way. just divide it into separate parts which can work by themselves. * You can run angularjs and angular at the same time in one page
and if you need to pass data from angularjs to angular I would do it in another way like using localstorage.
anyway it's really hard o understand with your explanations where is the problem, even with errors in the console , angular debugging take time.