I want to rephrase my problem stated above a little bit. After some messing around I realized with initial create-react-kotlin-app setup js files are just ignored and simply not included into final build, which was likely the main issue. Since I want to use both JS and Kotlin in one project I want to be able to compile both js files and kt files. Unfortunately, I wasn't able to find any information how such system can be setup easily. I found kotlin plugin for webpack but I wan't able to set it up and there is not much information online about it.
So, my question is, how to compile both kotlin files and js files in one react project (which uses create-react-app) if I have no intention to actually use react from kotlin, but want to be able to partially write application in kotlin and call it from js part?