I agree wholely with the other comments, this is a great set that it appears a significant amount of effort has been put into.
I'm not an IP law expert but my understanding is that such a product is best released under license, you could argue that it's derivative but if this were a GB I'd really not be comfortable with placing an order for this with such a question still outstanding, and I suspect a lot of vendors will wisely avoid it on the same grounds.
With regards the name, the word "Silmarillion" is subject to active trademarks in both the
US and the
UK for categories of goods that in my opinion a lawyer could argue keycaps to be - novelty items. I suspect the Tolkien estate holds the trademark more broadly in other territories too.
With trademarks, there's little to no room for fair use, especially as a product name - in order to remain protected, the holder has to be seen to enforce their trademark. Thus it's highly likely this will become subject to legal issues with the name as it stands.
