It might also be useful to remember where the names of the Valar come from to start with, so we can see why the 'simple is best' is the way to go here.
Manwë noun "Blessed Being"
(Letters:283), the Elder King and Lord of the Valar, spouse of Varda. The name is adopted and adapted from Valarin
Mānawenūz; names ending in -
wë were already frequent in Quenya
(WJ:399). In the
Etymologies derived from
MAN,
WEG.Cf.
Mánwen,
Mánwë the oldest Quenya forms of
Manwë, closer to the Valarin form
(WJ:399).
Mânawenûz "Blessed One, One (closest) in accord with Eru". In Quenya reduced and altered to produce
Manwë. (WJ:399)
Melko masc. name "Mighty One", name of the rebellious Vala, usually called
Melkor (MIL-IK, MOR; FS – MR:350 confirms that the form Melko is still valid in Tolkien's later Quenya, though not interpreted "Greedy One" as in the Etymologies
)
Melkor (spelt Melcor in VT49:6, 24, MR:362), masc. name: the rebellious Vala, the devil of the Silmarillion mythos. Older
(MET) form
Melkórë "Mighty-rising" (hence the interpretation "He that arises in power"), compare
órë #2. Oldest Q form *
mbelekōro (WJ:402).
Varda fem. name "the Sublime", name of a Valië, spouse of Manwë, the Queen of the Valar, called
Elbereth in Sindarin
(BARATH, BARÁD, WJ:402; in Letters:282 Varda is translated the "Lofty"). As a general adjective “sublime”, †
varda could still occur as a poetic word in verse
(PE17:23), but normal prose would apparently rather use the related word
varanda
Ulmo masc. name, used of the Vala of all waters
(ULU), interpreted "the Pourer" by folk etymology, but the name was actually adopted and adapted from Valarin
(WJ:400) ulu,
ullu "water" (WJ:400, 401).
Ulubôz,
Ullubôz a name containing
ulu,
ullu "water", adapted to Quenya as
Ulmo and interpreted "the Pourer" by folk etymology. (WJ:400)
aulë (1)
noun "invention"
(GAWA/GOWO); evidently connected to or associated with
Aulë, name of the Vala of craft
(GAWA/GOWO, TAN), spouse of Yavanna; the name is adopted and adapted from Valarin
(WJ:399)
A3ûlêz name of unknown meaning, altered to produce Quenya
Aulë. (WJ:399)
Yavanna, fem. name:
Yav-anna, “Fruit-gift”
(PE17:93) or "Fruit-giver", name of a Valië, spouse of Aulë, associated especially with plants
(YAB, ANA1; cf. yávë)
Nienna noun (name of a Valië, related to
nië = tear)
(NEI)
Tulkas (
Tulkass-, as in dat.sg.
Tulkassen) masc. name, used of a Vala, adopted and adapted from Valarin
(WJ:399, TULUK)
Tulukhastâz (sic - read Tulukhaštâz?) is supposedly a compound containing tulukha(n) "yellow" and (a)šata "hair of head", hence "the golden-haired". Adapted to Quenya as Tulkas. (WJ:399)
(but see tulca (1) ("k") adj. "firm, strong, immovable, steadfast" (TULUK))
nessa adj. "young"
(NETH), also
Nessa as name of a Valië, the spouse of Tulkas (adopted and adapted from Valarin,
or an archaic Elvish formation: WJ:404 vs. 416). Also called
Indis, "bride"
(NETH, NI1). The fem. name
Nessanië (UT:210) would seem to incorporate Nessa's name; the second element could mean "tear" (
nië), but since Nessa is not normally associated with sorrow, this #
nië is perhaps rather a variant of
ní "female" (compare
Tintanië as a variant of
Tintallë).
Námo (1) noun "Judge", name of a Vala, normally called Mandos, properly the place where he dwells (WJ:402)
Vairë (1) fem. name "the Weaver", name of a Valië, spouse of Mandos (Silm, WEY). The name is translated "Ever-weaving" in VT39:10, and it is implied that the archaic form was *Wairē rather than ¤Weirē, the reconstruction given in the Etymologies (entry WEY). Tolkien considered changing the name to
Vérë (PE17:33) One source glosses the literal meaning as “weaving” rather than “weaver” (PE17:191).
Irmo masc. name "Desirer", name of a Vala; normally called
Lórien, properly the place where he dwells
(WJ:402)
Estë fem. name "Repose, Rest"
(WJ:403, EZDĒ, SED), only used as name of a Valië
(WJ:404)
Oromë noun name of a Vala, adopted and adapted from Valarin. Observes Pengolodh, "the Eldar now take the name to singify 'horn-blowing' or 'horn-blower', but to the Valar it had no such meaning" (WJ:400-401, cf. SA:rom and ROM, TÁWAR in Etym, VT14:5).
Arômêz (in the source, the letter ô has a diacritic indicating that it is open and a
-like) a name adapted to Quenya as
Oromë and to Sindarin as
Araw. (WJ:400) According to Elvish folk etymology,
Oromë meant "horn-blowing" or "horn-blower", but the original Valarin name simply denotes this Vala and has no etymology beyond that (WJ:401).
Vána fem. name, a Valië, the wife of Oromë
(Silm, WJ:383); the
Etymologies gives
Vana with no long vowel
(BAN). The apparent meaning is *“beautiful (one)”, since she was “the most perfectly ‘beautiful’ in form and feature…representing the natural unmarred perfection of form in living things”
(PE17:150).
Ossë noun name of a Maia, adopted and adapted from Valarin
(WJ:400), though connected with the common noun
ossë "terror" in Etym
(GOS/GOTH)
Ošošai,
Oššai a name supposedly meaning "spuming, foaming", adapted to Quenya as
Ossai >
Ossë, Sindarin
Yssion,
Gaerys. (WJ:400)
Uinen (
Uinend-, as in dative
Uinenden) fem. name, used of a Maia, spouse of Ossë
(UY, NEN). Adopted and adapted from Valarin
(WJ:404), though it is also said that it contains -
nen "water"
(SA:nen); the latter explanation may be folk etymology. In the
Etymologies, the name is derived from the same stem
(UY) as
uilë "long trailing plant, especially seaweed".
Note that none of these are 'maiden crowned with a radiant garland' levels of complexity. They embody some aspect of the mind of Iluvatar, so the word for that thing they embody is their name. This makes me much more inclined to go with 'Fiery One' for Gothmog.
Valarin is the language of the Valar before the elves show up, so clearly the first season should be entirely in Valarin. Of course, Tolkien only gave us a few examples of what it sounded like, so it's not like we have any clue how to do that.
Here's what we know of Valarin:
http://folk.uib.no/hnohf/valarin.htm
Conveniently, one of the few vocab words we have is fire:
uruš "fire" (also
rušur) (WJ:401)
Which brings us back to Urumo, Urusmo, but introduces the possibility of Rusumo (or another looser variation, since these aren't translations but transliterations/adaptations.)
. 