The interoperability is both a blessing and a curse imo since it let us half-ass the integration by leaving a bunch of Java code unconverted. I could start refactoring everything but then my team would stop reviewing my PRs due to the diff size (and then my manager would eventually find out that I've been using up work time doing this instead of shipping features during crunch week).

I really much prefer Kotlin to Java. I just wish my team had actually had a commitment to it instead of just sorta using it with no migration plan.