Scriba respondet bonum tutorem non solum patrimonium, sed etiam pupillam ipsam servare debere.

Because Latin is using an indirect statement after respondet.

In a direct statement, you would expect:

bonus tutor ... debet

But in an indirect statement, Latin normally changes:

• the subject into the accusative
• the finite verb into an infinitive

So:

• bonus tutor → bonum tutorem
• debet → debere

That is why bonum tutorem is not nominative here.

Yes. It is the whole reported idea, dependent on scriba respondet.

A helpful way to see it is:

• scriba respondet = the clerk replies
• bonum tutorem ... servare debere = that a good guardian ought to protect...

So the sentence is built like this:

• main clause: Scriba respondet
• indirect statement: bonum tutorem non solum patrimonium, sed etiam pupillam ipsam servare debere

Because the two infinitives are doing different jobs.

• debere is the main verb of the indirect statement.
• servare depends on debere.

So debere means to owe / to be obliged / ought, and it commonly takes another infinitive:

• servare debet = he ought to protect
• in indirect statement: servare debere = to ought to protect / to be obliged to protect

A very literal breakdown is:

• debere = to be obliged
• servare = to protect

Together: to be obliged to protect

This is a very common pairing meaning:

• not only ... but also ...

Here it links two things that the guardian ought to protect:

• non solum patrimonium = not only the property/estate
• sed etiam pupillam ipsam = but also the ward herself

So the contrast is important: a good guardian must care not just for the money or inheritance, but for the girl herself.

They are both direct objects of servare.

The guardian is the one doing the protecting, and these are the things being protected:

• patrimonium = the estate/property
• pupillam ipsam = the ward herself

So the structure is:

• bonum tutorem = subject of the indirect statement
• servare = action
• patrimonium and pupillam ipsam = objects of that action

Because in an accusative-and-infinitive construction, the accusative noun before the infinitive is often the logical subject of the infinitive.

Also, the sentence makes best sense that way:

• a good guardian is the one who ought to protect
• the estate and the ward are the things protected

So Latin is not saying that someone answers a good guardian; it is saying that the clerk replies that a good guardian ought...

Ipsam adds emphasis: the ward herself.

Without ipsam, pupillam would simply mean the ward.

With ipsam, Latin stresses the contrast:

• not only her property
• but also her very person

This is exactly the sort of emphasis ipse, ipsa, ipsum often gives.

Latin word order is flexible, and ipse often comes after the noun it emphasizes.

So:

• pupillam ipsam

naturally means:

• the ward herself

Latin could sometimes place it differently for emphasis, but this order is perfectly normal.

Because Latin relies much more on case endings than on fixed word order.

English needs order to show function:

• the guardian protects the ward

Latin can show the roles through endings, so it can arrange words more freely for style or emphasis.

In this sentence, the order helps highlight the contrast:

• first the guardian
• then not only the estate
• then but also the ward herself
• finally the verbal idea servare debere

That final placement of the verb phrase is also very natural in Latin.

It most naturally means ought to or should, though context can make it stronger.

Debere originally has the sense to owe, and with an infinitive it often expresses duty or obligation:

• servare debere = to ought to protect
• smoother English: ought to protect, should protect, or sometimes must protect

In a moral or legal context like this one, ought to is often a good choice because it preserves the idea of duty.

It can mean several related things, depending on context:

• save
• preserve
• keep safe
• protect

Here protect or preserve fits best. The idea is not only preserving the ward’s estate, but also keeping the ward herself safe.

Yes. A direct version would be:

Bonus tutor non solum patrimonium, sed etiam pupillam ipsam servare debet.

Notice the two main changes from the indirect version:

• bonum tutorem → bonus tutor
• debere → debet

That comparison is a very useful way to understand the grammar of the original sentence.