I'd been using Java previously for research prototypes, Java was getting popular, and Kawa's property of running on the JVM seemed potentially practically very useful or critical, and I wanted it in my pocket.
I ended up moving primarily to PLT Scheme (aka Racket), but I would (and still do) always tell people about keeping some of the special Scheme implementations as backups. Kawa for JVM, Gambit for large numbers of threads and other properties, Chicken for its C compilation approach and significant community.
I think the JVM aspect was one of the keys to Clojure achieving more popularity than Racket. Though Clojure was also led from the top with a better command of industry application, and also focused outreach on the wealth of Common Lisp (CL) (sometimes called simply "Lisp" without qualification) developers, who as a whole seemed to be more seasoned veterans than our average Scheme/Racket developer. (Whereas Racket, though it also had and gained some very skilled developers, was led from the top towards research and CS education goals, and early developer outreach was maybe mostly about being out there among dozens of Scheme implementations, and trying to be attractive to move to, or to be tried first. Industry application understanding came up from the bottom, the funding at the top remained for academic goals, and none of the people with industry experience got into leadership. So, in hindsight, I suppose it's not surprising that Racket and all the Scheme people who went there never took off commercially, beyond a few random success stories, and that Clojure would end up winning more in that regard.)
If I get time to do more on Scheme/Racket, other than the occasional package maintenance, I'd probably re-focus on portability to at least a few Schemes, and Kawa would be among them. (Right now, I'm leaning towards investing side-project time in leveraging various background towards Rust -- partly for its merits, and partly to keep learning and integrating a breadth of topics. But Scheme is still worth learning beyond school assignments level, and very powerful and a joy to work with practically, iff you have the time to invest in leveling up, filling in missing bits, and pulling off the occasional magic. Scheme even has some influences on Rust, and maybe with additional influences possible.)