Sad decision, LUA is fast and does not need to be compiled for on the fly coding. To be honest I'm not a big fan of Java, although good games came out of it. With LUA I can implement something super quick and makes debugging super easy. With Java it will be a nightmare as well as a memory hog. I really hope you guys thought more of this before making a final decision.
... you do know that Rising World is for the most part Java, right? And while you are right about Lua allowing to build something quick and dirty, you still need to restart the entire game every time you make a change in your script as well.
And, for the sake of arguing, on one hand, with Java one could test their script in a mocking environment before launching the game, instead of starting and stopping the game a dozen times to find and fix issues. On the other hand, unless your Java project is requiring a few dozen sources and third party projects, etc. javac is quite acceptable. As for memory, you are picking your arguments at weird places, as the Lua-to-Java bridge (or any Lua-to-native bridge) requires a lot.... A LOT!! of wrappers and thus creates many memory buffers during a script's execution. While these buffers are cleaned and garbage collected and create very few memory leaks, you never have direct access to anything, and the abstraction layer is really a waste of CPU time.
Having an ease to edit something is usually in opposition with the end result (i.e. performance). And, in the end, the point of a script is to be executed, not edited
Now, I am not part of this decision, even though I have had a voice (that had more or less weight in the equation); but I not only support the migration, I believe it has long term benefits to the game on various and many aspects. Far more than continuing supporting a Lua API (which is nothing but limiting in Rising World). There is a reason why Minecraft have so many powerful game mods and why it works.... it uses Java as well. Not Lua. Just some food for thought.