If you think Kotlin is marginally better than Java, you probably have a superficial understanding of Kotlin. Kotlin is vastly better than Java, which isn't surprising because Kotlin was designed 15 years later with the explicit goal of being a better Java and fixing as many of Java's design mistakes as possible. For example, the designers of Kotlin went through the book "Effective Java" and tried to avoid the listed pitfalls by design.
Java will never get close to Kotlin because even though Java can, and thankfully does, still improve, it's too late to revise many of it design decisions, and large language features often need to be considered in a language's design from the start.
On Android, Kotlin is an even bigger win because Android uses an old Java version and has become Kotlin-first.
In my opinion, Java will remain the best choice for libraries that target multiple JVM languages. For everything else, I use Kotlin without thinking twice. Kotlin 2.0 laid the groundwork for toolchain improvements, which have indeed been a long-standing pain point.
Java will never get close to Kotlin because even though Java can, and thankfully does, still improve, it's too late to revise many of it design decisions, and large language features often need to be considered in a language's design from the start.
On Android, Kotlin is an even bigger win because Android uses an old Java version and has become Kotlin-first.
In my opinion, Java will remain the best choice for libraries that target multiple JVM languages. For everything else, I use Kotlin without thinking twice. Kotlin 2.0 laid the groundwork for toolchain improvements, which have indeed been a long-standing pain point.