WRT build systems: both Maven and Gradle are fully supported in Kotlin, with JetBrains provided plugins and IntelliJ knows how to work with them. So I am not sure why you would want more here. You say there's a highlighting issue, but I never saw such a thing, and wouldn't that be a minor IDE bug rather than a reason to develop a new build/package manager from scratch?
Finally, Kotlin avoids macros (compiler plugins) by choice. The idea is the built-in features let you customise the language enough without full blown AST rewriting.
Other than being MUCH faster to compile than Scala, kotlin is also much easier to read.
Also, Quasar is fantastic.