Is the main clause in the relative clause construct an actual clause?

Question

I know that relative clause compounds are generally made with the following format.

sentence/verb/adjective + noun

My Genki I textbook supports this with the following example of a relative clause compound, with the noun 学生 being italicized in English.

あそこで本をよんでいる学生はみちこさんです。

The student who is reading a book over there is Michiko.

However I remember browsing Japanesestackexchange last year and finding some users referring to the noun part of a relative clause compound as a 'main clause'. This has recently made me question where the noun/'main clause' ends in Japanese sentences.

Edit: In other words, using the above example once more; is the entirety of 学生はみちこさんです the main clause which the relative clause modifies, or is it only the noun that is being modified; thereby restarting the sentence after the noun?

I'm asking as in the word doc for a book I'm translating I have two different examples of relative clause compounds, and I'm wondering which example is correct.

Example 1: 返事をした女の子がこちらに近づき、僕の手にナイフを[握]{にぎ}らせる。

Relative Clause: 返事をした

Main Clause: 女の子がこちらに近づき

Example 2: 荒野を渡る風よりもなお、アインの声は冷たかった。

Relative Clause: 渡る

Main Clause/noun: 風

Answer 1

I know that relative clauses are generally made with the following format.

sentence/verb/adjective + noun

Strictly speaking, a relative clause refers only to the part before the modified noun. 本をよんでいる学生 is not a relative clause although it has a relative clause. The grammatically correct way to explain this phrase is "本を読んでいる is a relative clause which modifies 学生".

_{(On this site, you may see people say "本を読んでいる学生 is a relative clause" for the sake of brevity, but technically speaking that's not the most correct explanation.)}

Do you understand what a clause (節) is in general? Very roughly speaking, it's a predicate associated with corresponding subject/object/etc (see this). The main clause of a sentence refers to the outermost clause (=subject-predicate pair). In your example sentence:

• Main clause:
  学生はみちこさんです
  The student is Michiko
• Relative clause (modifying 学生/student):
  あそこで本を読んでいる
  who is reading a book over there

referring to the noun part of a relative clause as a 'main clause'.

"The noun part of a relative clause" is not part of the relative clause in the first place. In your example, 学生 belongs to the main clause.

where the noun/'main clause' ends (therefore the end of the total relative clause construct) in Japanese sentences.

In Japanese, when a relative clause ends, the main clause (re)starts (unless several relative clauses are deeply nested). In a regular Japanese sentence, the main clause ends always at the end of the sentence.

In English, a relative clause starts with a relative pronoun (that/which/who/where/etc, although that may be omitted), but the modified noun before it is not part of the relative clause.

Is the main clause in the relative clause construct a actual clause?

This question doesn't make sense to me. The main clause refers to the outermost clause in a sentence. A relative clause never contains a main clause. (A sentence may have two or more main clauses. See: compound sentence)

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EDIT:

is the entirety of 学生はみちこさんです the main clause which the relative clause modifies, or is it only the noun that is being modified

A clause is a noun? If you know what a clause is, you don't have to ask a question like this. A clause is not a noun, but basically a subject-predicate pair. And a relative clause modifies a noun, not a clause!

• Relative clause: 返事をした (modifies 女の子)
• Main clause 1: 女の子がこちらに近づき
• Main clause 2: (女の子が)僕の手にナイフを握らせる

• Relative clause: 荒野を渡る (modifies 風)
• Main clause: 風よりもなおアインの声は冷たかった

Note that each clause (main or relative) has one and only one predicate (an adjective or a verb).