Yep,
Balrogs were
Maiar by the time of this note, and according to the
Annals of Aman -- the abandoned typescript version AAm
* section 30:
"And in Utumno he multiplied the race of the evil spirits that followed him, the Umaiar, of whom the chief were those demons whom the Elves afterwards named the Balrogath."
CJRT writes that there seems no way to determine with certainty when AAm
* was made, but he thinks or feels that it belongs to the early 1950s, and if so, I needn't look further to also say that the Balrogs were Maiar at an external time when they were conceived of as numerous.
CJRT's edits to surviving "Numerous Balrog" passages
Despite
Tolkien's famed note to drastically reduce Balrog numbers (and its attending revision to a passage in AAM), so far I've counted 4 surviving references to numerous Balrogs. Here they are -- followed by the
alterations made to
The Silmarillion by Christopher Tolkien:
1: "Wherefore each embassy came with greater force than was agreed, but Morgoth sent the greater, and they were Balrogs. Maidros was ambushed..." Of The Siege of
Angband (
Quenta Silmarillion)
[] "... but Morgoth sent the more, and there were Balrogs." Of The Return of the
Noldor (The Silmarillion)
2: "Sauron came against Orodreth, the warden of the tower, with a host of Balrogs." Of the Ruin of
Beleriand And the Fall of
Fingolfin (Quenta Silmarillion)
[] ".. named Gorthaur, came against Orodreth, the warden of the tower upon Tol Sirion." Of The Ruin Of Beleriand (The Silmarillion)
3: "There came wolves and serpents, and there came Balrogs one thousand,..." Of the Fourth Battle: Nírnaith Arnediad (Quenta Silmarillion)
[] "There came wolves and wolfriders, and there came Balrogs, and dragons..." Of The Fifth Battle (The Silmarillion)
4. The Grey Annals contains
"Balrogs a thousand" §230, but nothing is noted as to any changes in the later 1950s.
Notes to these numbered passages
1 This description (from the QS tradition) survived into LQS despite a number of other post
Lord of the Rings revisions to this chapter.
2 This example (Orodreth and etc) also was not revised -- with Tolkien even altering §143 of the chapter, but not the "host" of Balrogs passage.
3 Another survival, but noting CJRT's description under
The Last Chapters Of The Quenta Silmarillion, possibly JRRT never really got around to "truly" revising this chapter in any case.