As I think I understand these terms (so far) . . .
Arda “
realm” used as a proper name refers to the world as the realm of
Manwe, but according to a text in
Morgoth's Ring, properly speaking, this kingdom extends beyond the world, including
Aman and the rest of the Solar System (I lifted this from
Parf Edhellen instead of actually doing the work).
I don't know (yet) if the new book
The Nature of Middle-Earth says something different here, but generally speaking, I'm vaguely aware that
Tolkien has noted something "new" about Aman, and I haven't got around to reading this section yet.
Ambar "world, the great habitation" . . .
. . . but according to the text
Fate And Free Will: "the full implication of this word cannot be understood without reference to Eldarin views and ideas concerning "fate" and "free will" ( . . . ) "the sense "world" applied usually to this Earth -- is mainly derived from sense "settlement": "the great habitation" ( . . . )
as "home of speaking
creatures" esp.
Elves and
Men."
Tolkien goes on here:
"But though mbar- was naturally mostly used of the activities and purposes of rational creatures, it was not limited to these. It thus could refer to the conditions and established (physical) processes of the Earth (as established at its creation directly or mediately by
Eru), which was part of Ea, the Universe, and so approached in some uses the sense "Fate", according to Eldarin thought on the subject. Thus Q.
ambarmenie "the way of the world ( . . . ) , the fixed, and by "creatures" unalterable, conditions in which they lived.
I note that the explanation according to
Words, Phrases, and Passages (PE 17) is differently worded, and notes the difference between how the Eldar might use the word, versus the
Numenoreans for example (and brings in the "doom" of
Túrin Turambar as well).
Concerning the diaeresis (two dots), while I realize my opinion given twice doesn't count as a second opinion, to ramble a bit more: there's no difference in the pronunciation of the vowels with respect
to Ea, Eä, or Ëa -- the function of the dots here is to try to inform the reader that this word has two syllables (or that
Eärendil has four syllables).
As an English speaker, for example, I know how to pronounce the word cooperate without needing
to see co-operate or coöperate. And here I'm going to assume that
Quenya speakers know that -ea-
is two syllables without needing to mark this in some way . . .
. . . or in any case, what I can say is that Tolkien himself makes no marks equivalent to the diaeresis in his
tengwar transcription of Namárië, which includes words in the Roman version like
laurië and Oiolossëo
. . .
. . . and namárië too
And since it was me who told you, please forgive my pedantry here, but the diaeresis can be ignored when
transcribing Quenya. In your example above, for example, the word Eä has not been translated,
it's the same Quenya word of course, written with a different writing system.
Quenya is a language while the Tengwar of
Feanor can be used to write various
languages.
