Oh boy, this brings back some fond memories from around 2013-2015.
Around that time I wrote very similar 3D map library (using three.js and cdlod-type approach for terrain rendering) and created custom AngularJS directives for similar purposes like your React library.
Sadly, my code was closed source and the startup I was working in went bankcrupt and my code went with it.
Thanks for sharing your project :)