I dont understand your question
Do you want to understand the architecture of ROO or Architecture of the code emitted.
You can come up with the same result without ROO. I think its pretty well documented architechture (in Spring Manual plus books which are written for Spring and blog entries)
If you have any particular question (why X, and What is Y for) then we may be able to help. To be honest, most of open source development happens by looking at code and that too Test code (and not from diagrams as it is taught in the M$ camp)
Just my 2 cents