Si fueran defectuosos, el comprador pediría un reembolso.

Because this sentence is expressing a hypothetical situation: if they were defective, the buyer would ask for a refund.

A very common Spanish pattern is:

• si + imperfect subjunctive
• conditional

So here:

• si fueran defectuosos = if they were defective
• el comprador pediría un reembolso = the buyer would ask for a refund

This is the normal structure for an unreal or unlikely condition in the present or future.

Because after si in this kind of hypothetical sentence, Spanish uses the imperfect subjunctive, not the conditional.

So Spanish says:

• Si fueran defectuosos, ...

Not:

• Si serían defectuosos, ... ✘

This is one of the most important patterns to remember:

• Si + imperfect subjunctive, conditional

For example:

• Si tuviera dinero, compraría más.
• Si fuera más fácil, lo haríamos.

So fueran is correct because it is the imperfect subjunctive of ser.

Fueran is the imperfect subjunctive form of ser.

Here it corresponds to they were in a hypothetical sense.

The subject is not stated directly, but it is understood from context. It could refer to something like:

• los productos
• los artículos
• los bienes

So fueran defectuosos means were defective, referring to some plural items.

Because it agrees with the thing being described.

Spanish adjectives must agree in number and usually gender with the noun they refer to.

So:

• defectuoso = singular masculine
• defectuosa = singular feminine
• defectuosos = plural masculine
• defectuosas = plural feminine

In this sentence, the noun is omitted but understood to be something plural, probably masculine or mixed-gender, such as los productos. That is why the adjective is defectuosos.

Yes. Fueran and fuesen are both correct imperfect subjunctive forms of ser.

So both of these are grammatical:

• Si fueran defectuosos, el comprador pediría un reembolso.
• Si fuesen defectuosos, el comprador pediría un reembolso.

In modern everyday Spanish, -ra forms like fueran are usually more common than -se forms like fuesen, but both are standard.

Yes, but that changes the meaning.

• Si son defectuosos, el comprador pedirá un reembolso
  = If they are defective, the buyer will ask for a refund
  This sounds like a real or possible future condition.

• Si fueran defectuosos, el comprador pediría un reembolso
  = If they were defective, the buyer would ask for a refund
  This is more hypothetical or less direct.

So the original sentence is not talking about a straightforward future possibility; it is presenting a more theoretical situation.

It is normally about a present or future hypothetical situation, not a past one.

Even though English uses were, the meaning is something like:

• if they turned out to be defective
• if they were defective (in that case)

If you wanted a past counterfactual meaning, Spanish would usually use:

• Si hubieran sido defectuosos, el comprador habría pedido un reembolso.

That means:

• If they had been defective, the buyer would have asked for a refund.

So the original sentence is the present/future hypothetical pattern.

Because el comprador can be used in a generic sense, especially in formal, commercial, or legal-style language.

Here, el comprador means something like:

• the buyer
• a buyer, in that role
• the purchaser

It sounds like a general rule or policy.

Compare:

• el comprador = the buyer, as a category or defined role
• un comprador = a buyer, one unspecified individual

In business or legal contexts, Spanish often uses the definite article this way.

Reembolso focuses on the money being refunded.

• pedir un reembolso = to ask for a refund

Devolución often focuses more on the return process or sending the item back, though in many contexts it can also be connected with getting your money back.

In commercial Spanish, both words are common, but they are not always exactly the same:

• reembolso = refund
• devolución = return

So pedir un reembolso specifically highlights requesting the money back.

Yes. You can put the main clause first:

• El comprador pediría un reembolso si fueran defectuosos.

This means the same thing.

When the si clause comes first, a comma is normally used:

• Si fueran defectuosos, el comprador pediría un reembolso.

When the si clause comes second, the comma is usually omitted:

• El comprador pediría un reembolso si fueran defectuosos.

The accent mark shows the correct stress: pe-di-RÍ-a.

Pediría is the conditional form of pedir, and conditional endings in Spanish have a written accent:

• pediría
• pedirías
• pediríamos
• pediríais
• pedirían

So the accent is a normal part of the conditional ending, not something unusual about this verb.

They are very similar, but the tone is a little different.

• pediría = would ask for
• solicitaría = would request

Solicitaría sounds more formal and administrative.
Pediría is more neutral and common.

So in a business or legal text, you might see either:

• El comprador pediría un reembolso.
• El comprador solicitaría un reembolso.

Both are correct, but solicitaría sounds slightly more formal.

Yes, but that is completely normal in Spanish.

Spanish often omits subject pronouns when the meaning is clear from the verb form or the context. Here, fueran implies they were.

The sentence assumes you already know what they are, for example:

• the products
• the goods
• the items

So Spanish does not need to say ellos or repeat the noun if the context already makes it clear.