A pleasant room it was as any party need desire to muster in on a cold November evening.(original)
Question:
Is the original complete one and grammatically correct?
I guess:
to muster in a pleasant room ( the " a pleasant room" for "it was a pleasant room"?)?
what is the subject of the original, and its main verb? and its object?
it seems to me that the original is not a complete sentence but something like: Any party need to desire to muster in such "a pleasant room as "a pleasant room"
for " it was a pleasant room" on a cold November evening, but in fact, they have not mustered in.
Is my guess correct?
By the way I still really don't understand the original, and especially its structure.

Question

A pleasant room it was as any party need desire to muster in on a cold November evening.(original)
Question:  
Is the original complete one and grammatically correct?
I guess:
to muster in a pleasant room (  the " a pleasant room" for  "it was a pleasant room"?)?
what is the subject of the original, and its main verb? and its object?
it seems to me that the original is not a complete sentence but something like: Any party need to desire to muster in such "a pleasant room as "a pleasant room"  
for " it was a pleasant room" on a cold November evening, but in fact, they have not mustered in.
Is my guess correct?
By the way I still really don't understand the original,  and especially its  structure.

Answer

It makes zero sense to me. Where is it from?

Answer

In addition to the odd word order, ‘muster’ isn’t used this way in American English any more. For people it usually it refers to military troops. It can also mean ‘gather’ for supplies, and it is found in certain expressions such as ‘to muster courage’.

Let’s gather in the dining room. (Ok)
Let’s muster in the dining room. (No)

Answer

The style of the sentence is tortuous and convoluted, but it does make sense.  The words are arranged in an atypical manner, but otherwise it is almost normal:

"It was as pleasant a room as any party need desire (in which) to muster on a cold November evening."

"Party", here, means "group of people".
"Muster", here, means "assemble".

If you want practice with elaborate sentences like this one, pick up any novel by Henry James.  His sentences make this one look like a piece of cake.

Answer

Yes it is complete and correct. But it is intentionally worded poetically, not for clarity. Even for most native speakers, it's difficult to read and instantly understand.

Personally, I avoid reading such things. If they had anything important to say / anything worth listening to, it would be worded much more clearly, I think.