Most but not all of your question was answered already. I will respond to what wasn't addressed, and add a bit to what was.
Both sentences A and B are grammatically correct, although they usually have different meanings, depending on full context of use.
Yes, sentences C and D have the same structure and meaning as sentence B. Next, the inquiry about Sentence C:
Later, Boeing sent Japan some very sophisticated CAD/CAM manufacturing
Sentence C can mean that Boeing sent manufacturing tech to the national government of Japan. It can also mean that Boeing sent this tech to several particular companies in Japan.
If the subject of B is "Japan", then the sentence would be
Japan sent Australia a sick koala.
This would also be acceptable and correct, just as B, C, and D are.
The use of "to Australia" in sentence A may or may not indicate physical geography. That's why I don't think it supports the locative expression explanation suggested by the linguistics guy in the comments, although it would be nice if it did. (I am one of those terrible prescriptivist types.)
In summary, as one of the other comment persons has said, the meaning of both sentences is context dependent, but both are correct grammatically in the English language as it used today. 'Australia' might refer to
- the physical continent of Australia
- the government and polity of Australia
- a branch of a private company's offices located in Australia
- an embassy of the nation of Australia that is physically located anywhere in the world. By virtue of it being an embassy, it is considered to be part of Australia's sovereign domain. For example, consider how Julian Assange can take refuge in the Ecuadorean embassy in London, or how escapees from the former East Germany would run to the American embassy in Berlin and if they made it to the doorway, they were free from Erich Honecker's regime that disallowed emigration with a wall to keep in, not to keep them out.