Just a nit, but you don't "write in Tengwar." The word 'tengwar' roughly equates to the table of letters. That would be like saying you "write in Alphabet."

You might say you write using the Feanorian characters, or if you're a true elf-nut, you might write in the Sindarin language (or some other dialect).

It's nice to see that the Unicode has a code point for the Tengwar. I don't think it's really complete as Tolkien used quite a few characters not described in LotR appendices, but it's flattering to the fans that it was considered.