I've been trying to get non-android teams I've been in to use Kotlin instead of Java for a long time. I think the primary blocker from switching is that most decisions they make are conservative and switching to Kotlin is not seen as conservative. Java is an extremely conservative language, there's basically no risk in using it and the perception I think is the same. When engineers try to sell Kotlin, I think they usually try to sell the awesome features and time saving, but what they should be selling as well is the reduction of risk and that switching can be a gradual process
I haven't tried making this argument yet, and I intend to with some well made slides so that I can finally get away from using a really obsolete language and start using one that brings me joy 🙂