The Word Break rules that interact with the Word Dictionary need to be cleaned up.
characters that are handled by the dictionary should be excluded from other character classes that participate in other rule based breaks.
The best handling of control, format, combining and extend characters within dictionary regions needs to be understood. What should tag onto the end of a word? Should anything be able to appear in the middle of a word without causing a break?
The Monkey test should be extended to include dictionary characters, so that the transitions between non-dictionary and dictionary ranges see some testing. (It can just use RBBI to break the dictionary runs)