He did not want to *The Hobbit* and *LOTR* to be even considered apart in any way. 

In one of his letters Tolkien explicitly states that he regrets deeply the language for adolescents he used in *The Hobbit*. Unfortunately I don't have the book with me, so can't reference more precisely, but it definitely is there.

This is somewhat partial answer to the question: yes, it can be inferred and/or implied from various texts that most of his works were "translations" from original manuscripts, but there was also a very specific decision on the kids' language used in *The Hobbit*, which muddies the water on the issue the OP is asking about.

Like I said, I don't have the book on me, but the passage was to the effect of: 

> "in retrospect language for children that was used in *The
> Hobbit" was a bad idea".