The whole thread is about primarily Common Lisp; people who enjoy the design choices made by the CL standardization committee and subsequent evolution of the language's ecosystem would most likely want to know that there exists a proper CL implementation for JVM.
As for being a hard sell - my personal experience is that if you're in a position that allows you to choose your implementation language, in most cases you can choose Brainfuck and nobody will care. As an example, I introduced F#, Erlang, Elixir and a bit of Prolog to a Python shop that way: all that mattered in these cases was whether the code worked, and it did, so no one complained. The Erlang microservice actually outlived the project it was written for by a year and a half.
On the other hand (still, in my experience) if you're not in a position where you can choose your language you're basically screwed, and should stop trying to convince your team to switch to something else. You have almost no chance of succeeding and a high chance of disrupting teamwork by pushing your opinions on others.
So I was thinking about the former situation, where you have some degree of freedom of choice and can decide the language on technical merits alone.
The latest release (1.5) was earlier this month.
it's common lisp. if the language spec hasn't changed, and your code works, you don't really need to change the interpreter.
Possible tip: sneak in ABCL when they're not looking. ABCL is a Common Lisp implementation for JVM, with (what seems like) relatively OK interop between Lisp and Java code.