So I was going through the sentence-syntax lesson, editing it and preparing it for the book, and after working on it non-stop for about 12 hours (forgot to eat lunch or dinner, I was so absorbed into it) I came up with a new idea for how to handle "en estar" and "estathar aen". Maybe I'm a little loopy from low-blood sugar and what I came up with is nonsense best ignored, I have no idea. So I'm sharing it with you guys to get it picked apart before I add it to my book.

The crux of it is - these both are passive voice. We can't be sure what exactly else is going on with them, but passive voice - that is pretty certain. I think that this passive voice syntax was abandoned in Tolkien's later Sindarin, since we've got "Noun [copula] past participle" for the passive voice attested later on.

And thus, a new idiom grows in my mind:
noun1 noun2 estannen.
noun1 is called noun2.

Noun2 isn't mutated.

And then, because of how one introduces oneself (myself Fiona - Im Fiona) which means that the name avoids being mutated as a direct object - we'd use "im" instead.

im noun2 estannen.
myself is called noun2 / I'm called noun2.

So, is this a nonsense interpretation or am I on to something? (whoa, sentences are getting hard to string together, not sure how understandable all of that will be)