About scripting, I've been really disappointed with it.
Seems like there are 3 main options and they are all half-baked IMO.
Groovy - must be fast since it turns the script into byte code and runs it in the JVM. Problem is that it is a whole new language that is similar but different to java. You can't just cut and paste java code into and out of your program. http://groovy.codehaus.org/
F3 - Hasn't been fully released yet and it is not real java either. http://blogs.sun.com/chrisoliver/entry/f3
BeanShell - Is meant to be like pure Java but there are lots of bugs. eg declaring an array can only be done like String anArray = ...; Also the error reporting isn't very good and the project hasn't been active since mid-2005 it seems. Unlike Groovy the code isn't turned into bytecode and fed to the JVM, instead it manipulates the objects using Reflection which is slower. http://www.beanshell.org/index.html
I hadn't heard of Lua Java but it looks OK if you are already familiar with it... but once you've perfected the AI code wouldn't you want to stick it in the Java code with the rest of the program?