Soror iterum modulatur, et etiam chorus nunc rectius cantat.

Because modulatur comes from a deponent verb: modulor, modulari, modulatus sum.

Deponent verbs are a special group in Latin:

• they have passive-looking forms
• but they have active meanings

So modulatur looks like he/she/it is being..., but it actually means he/she sings melodiously / modulates / makes melody.

In other words:

• soror modulatur = the sister is performing the action
• the form is grammatically deponent, not truly passive

Soror is nominative singular.

You can tell because it is the subject of modulatur. In this sentence, soror is the one doing the action.

A few helpful points:

• soror is a third-declension noun
• its dictionary form is soror, sororis
• the nominative singular is simply soror

So here:

• soror = subject
• modulatur = verb agreeing with that singular subject

Iterum is an adverb, meaning again.

It modifies the verb modulatur, telling you how often or in what repeated way the action happens:

• soror iterum modulatur = the sister sings again

Like many adverbs in Latin, iterum can often move around without changing the basic meaning very much. Its placement here is natural, but Latin word order is flexible.

They are related in meaning, but they do different jobs here.

• et = and
• etiam = also, even

So:

• et connects the two clauses
• etiam adds the idea that the chorus too is included

A useful way to think of it:

• et joins
• etiam emphasizes addition

So the sentence is not just X happens and Y happens; it is more like:

• X happens, and the chorus also...

Because in Latin, chorus is a singular noun grammatically.

Even if it refers to a group, Latin treats chorus as one unit here, so the verb is singular:

• chorus ... cantat
• not cantant

This is similar to how English can sometimes treat collective words as singular, depending on style:

• the team is winning

So in Latin grammar:

• chorus = singular subject
• cantat = singular verb

Chorus is also nominative singular.

It is the subject of cantat in the second clause:

• etiam chorus nunc rectius cantat

Even though it comes after etiam, it is still the noun doing the action, so nominative makes sense.

Also, chorus is a Greek loanword used in Latin, usually treated as a second-declension masculine noun.

Because rectius is the comparative adverb.

Compare:

• recte = correctly
• rectius = more correctly / better

So the sentence is not just saying that the chorus sings correctly. It says the chorus sings more correctly than before, or better in that respect.

This comes from the adjective rectus:

• adjective: rectus = right, correct
• adverb: recte = correctly
• comparative adverb: rectius = more correctly

This is a very common Latin pattern:

• clare = clearly
• clarius = more clearly

Nunc is an adverb meaning now.

It tells you the time of the action:

• chorus nunc rectius cantat = the chorus now sings more correctly

It may suggest a contrast with an earlier moment:

• before, the chorus was not singing as well
• now, it is doing better

Like other Latin adverbs, nunc has fairly flexible placement. Its position here is perfectly normal.

Yes, Latin could arrange them differently.

Latin word order is much more flexible than English word order because the endings often show the grammatical roles. So the sentence could be reordered in several ways without changing the core meaning.

For example, Latin uses word order mainly for:

• emphasis
• style
• rhythm

In this sentence:

• soror comes first, giving the first clause a clear subject
• iterum stands near modulatur
• etiam chorus highlights that the chorus too is involved
• nunc rectius groups the time idea and the comparative idea before cantat

So the order is meaningful stylistically, but not as rigid as in English.

Yes. Both modulatur and cantat are present tense, third person singular.

So grammatically we have:

• modulatur = she sings / is singing melodiously
• cantat = he/she/it sings / is singing

More specifically:

• modulatur = present indicative, 3rd singular, deponent
• cantat = present indicative, 3rd singular, active

That is why the two clauses feel parallel:

• one singular subject + one present-tense verb
• then another singular subject + another present-tense verb

Yes, they are closely related, but they are not exactly identical.

• cantat is the ordinary verb to sing
• modulatur suggests something like to sing melodiously, to modulate, or to produce melody with expression

So the author may be varying the diction slightly rather than repeating the exact same verb twice.

This is common in Latin:

• one verb can be more general
• another can be more refined or stylistically marked

So the difference is mostly one of shade and style, not a complete change of action.