Se a diretora tivesse visto o boletim antes, teria chamado a mãe.

This is the standard Portuguese pattern for a counterfactual past condition: an if-clause about something that did not happen in the past, followed by the result that also did not happen.

• Se a diretora tivesse visto o boletim antes = If the principal had seen the report card earlier
• teria chamado a mãe = she would have called the mother

In Portuguese, this pattern is usually:

• se
  • pluperfect subjunctive
• conditional perfect

So this sentence is the equivalent of English If X had happened, Y would have happened.

Tivesse visto is the pluperfect subjunctive (pretérito mais-que-perfeito do subjuntivo).

It is formed with:

• tivesse = imperfect subjunctive of ter
• visto = past participle of ver

So:

• ter visto = to have seen
• tivesse visto = had seen, in a subjunctive/conditional context

This tense is very common after se when you are talking about an unreal past situation.

Teria chamado is the conditional perfect.

It is formed with:

• teria = conditional of ter
• chamado = past participle of chamar

So:

• teria chamado = would have called

This is used for the result of an unreal past condition.

Because the sentence is talking about a situation that is hypothetical and contrary to fact.

The idea is:

• The principal did not see the report card earlier.
• Because of that, she did not call the mother.

When Portuguese uses if in this kind of unreal past scenario, it normally uses the subjunctive in the se-clause.

Compare:

• Se ela visse... = If she saw / were to see...
• Se ela tivesse visto... = If she had seen...

The second one is specifically about an unreal situation in the past.

Because tivesse visto is a compound tense.

In Portuguese, compound tenses are made with:

• an auxiliary verb, here ter
• a past participle, here visto

So:

• ver = infinitive, to see
• viu = simple past, saw
• visto = past participle, used with ter or haver

Examples:

• Ela viu o boletim. = She saw the report card.
• Ela tinha visto o boletim. = She had seen the report card.
• Se ela tivesse visto o boletim... = If she had seen the report card...

In this sentence, boletim most likely means report card or school grade report.

In Brazilian Portuguese, boletim can have different meanings depending on context, such as:

• boletim escolar = school report card
• boletim de ocorrência = police report
• boletim informativo = bulletin/news update

Because the sentence mentions a diretora and a mãe, the school meaning is the natural one here.

Literally, diretora means female director/head. In a school context, it is often best translated as the principal or the headmistress/head of the school, depending on the variety of English you want.

So in this sentence, the principal is probably the most natural English meaning.

Also note:

• diretor = male director/principal
• diretora = female director/principal

Portuguese often uses the + family noun where English would often use a possessive like her mother.

So:

• chamou a mãe can mean called the mother
• in context, it often naturally means called her mother or called the student’s mother

Portuguese does not always need to make possession explicit if the context already makes it clear.

If you wanted to be more explicit, you could say:

• teria chamado a mãe dela
• teria chamado sua mãe

But the original sentence sounds natural without that.

Because Portuguese often omits subject pronouns when the subject is clear from the verb or from context.

Here, the subject of both clauses is a diretora. So after mentioning it once, Portuguese does not need to repeat it:

• Se a diretora tivesse visto o boletim antes, teria chamado a mãe.

The understood subject of teria chamado is still a diretora.

If you wanted, you could say:

• ..., ela teria chamado a mãe.

But it is not necessary.

Antes means before or earlier.

In this sentence, it means that the principal would have acted differently if she had seen the report card earlier than she actually did.

So the sense is:

• antes = earlier / beforehand

A very natural English translation would be:

• If the principal had seen the report card earlier, she would have called the mother.

You could also see similar expressions like:

• antes disso = before that
• mais cedo = earlier

In many contexts, antes and mais cedo can be close in meaning.

Yes, very often.

For example:

• Se a diretora tivesse visto o boletim mais cedo, teria chamado a mãe.

This sounds very natural too and means almost the same thing: If the principal had seen the report card earlier...

Very roughly:

• antes = before
• mais cedo = earlier / sooner

In this sentence, both work well.

Not if you want exactly the same meaning.

• Se a diretora tivesse visto o boletim antes... = If the principal had seen the report card earlier...
• Se a diretora visse o boletim antes... = If the principal saw / were to see the report card earlier...

The version with visse uses the imperfect subjunctive, not the pluperfect subjunctive, so it does not clearly express had seen in the past.

If the meaning is specifically an unreal past situation, tivesse visto is the correct choice.

Yes, grammatically it can.

• Se a diretora houvesse visto o boletim antes, teria chamado a mãe.

This is correct, but in everyday Brazilian Portuguese, tivesse visto is much more common and natural.

Both mean the same thing here. Very generally:

• tivesse visto = more common in normal speech and writing
• houvesse visto = correct, but often more formal or literary

Portuguese uses definite articles much more often than English.

So where English might say:

• the principal
• the mother
• sometimes even just mother in special contexts

Portuguese naturally says:

• a diretora
• a mãe

This is completely normal. In Brazilian Portuguese, articles are especially common before nouns referring to specific people or roles.

The structure is:

• Se
  • subject + verb phrase + object + time word,
    then
• result clause

So here:

• Se = if
• a diretora = the principal
• tivesse visto = had seen
• o boletim = the report card
• antes = earlier / before
• teria chamado = would have called
• a mãe = the mother

A very literal map is:

• If the principal had seen the report card earlier, would have called the mother.

In normal English, you supply the subject again:

• If the principal had seen the report card earlier, she would have called the mother.

Yes, Brazilians really do say sentences like this. It is standard and natural.

That said, in very casual speech, people sometimes simplify structures, but the form here is completely normal and idiomatic in Brazilian Portuguese.

So this is a very useful model sentence for learning how to express:

• If X had happened, Y would have happened.

A very useful pattern is:

• Se + imperfect subjunctive, conditional
  for unreal present/future situations
• Se + pluperfect subjunctive, conditional perfect
  for unreal past situations

Examples:

• Se eu tivesse dinheiro, viajaria.
  = If I had money, I would travel.

• Se eu tivesse visto a mensagem, teria respondido.
  = If I had seen the message, I would have replied.

Your sentence follows the second pattern:

• Se a diretora tivesse visto o boletim antes, teria chamado a mãe.

That is one of the most important conditional structures in Portuguese.