I just did an Amazon search under Tolkien for literary analysis, critique and commentary and what do you know? Nothing!!
Now, that is just too odd, IMO. There should be reams of scholarly discussion.
But, I found this
https://www.amazon.com/Beren-Luthien-Summary-Analysis-Summarease/dp/1548310409/ref=sr_1_2?s=books&ie=UTF8&qid=1524344072&sr=1-2&keywords=Tolkein++analysis
The process sounds interesting and perhaps hints at a route around your dilemma.
What about a linguistic approach based on interwoven context, not *invented language*? And leave Tolkien out of the title/keywords. Concentrate on your method of analysis. Just a thought. Maybe add a chapter on Klingon or some other invented language (GoT). Methodology should be protectable* in & of itself and not litigatable* as violation of the franchise copyright.
[*N.B.: probably not words.]
I am not an aficionado and have read none of J.R.R. But my inner linguistic nerd is squawking that this is not to be borne! How dare they scoff at anyone’s analysis and critique!!! Glad I am not supporting their monopoly. 5 years of work is, in and of itself, a scholarly endeavor worthy of compensation. Have you consulted a literary attorney? (yeah, I know what they can charge. :(
I suppose the cash cow supports a bevy of lawyers.
I am a bit surprised you found almost nothing in your search. For example, there is another dictionary in print - authorized by the Tolkien estate - but it is much older and not nearly as extensive as my posting. If the 'Lord' turns a nice return on his effort, I imagine the estate will get in touch.
At any rate, it is water under the bridge for me; I have moved on as I navigate the autumn of my life. The work stands, or falls, as my monument. Thanks again.