Aunque la entrevista no salió perfecta, mi hermana dice que no fue un fracaso.

That is a very common question.

Here salir does not mean to leave. In Spanish, salir is also often used to talk about the result of something, especially events, plans, food, exams, interviews, and projects.

So:

• La entrevista no salió perfecta = The interview didn’t go perfectly
• more literally = The interview didn’t turn out perfect

Some similar examples:

• La tortilla salió muy bien = The omelette turned out very well
• El examen me salió fatal = The exam went terribly for me
• Todo salió mal = Everything went wrong

So in this sentence, salió is about how the interview turned out.

Because salir and ser do slightly different jobs here.

• No salió perfecta focuses on the outcome or how things went
• No fue perfecta would mean it wasn’t perfect, which is also possible, but sounds a bit more direct and less idiomatic in this kind of context

So:

• La entrevista no salió perfecta = The interview didn’t go perfectly
• La entrevista no fue perfecta = The interview wasn’t perfect

Both can work, but salió is especially natural when talking about how an event turned out.

Because the interview is seen as a finished, completed event.

The preterite salió presents the interview as a whole, completed thing:

• salió = turned out / went

That fits because the interview already happened.

If you used the imperfect, salía, it would usually suggest something ongoing, habitual, or backgrounded, which does not fit well here.

The same idea applies later with fue:

• no fue un fracaso = it was not a failure

Both verbs refer to a completed past event.

Because perfecta agrees with la entrevista, which is a feminine singular noun.

In Spanish, adjectives usually match the noun in:

• gender
• number

So:

• el examen perfecto
• la entrevista perfecta
• los resultados perfectos
• las respuestas perfectas

Here:

• entrevista = feminine singular
• so perfecta must also be feminine singular

Yes, aunque can be followed by either indicative or subjunctive, depending on meaning.

Here we have:

• Aunque la entrevista no salió perfecta...

The speaker is talking about something understood as a real fact: the interview actually happened, and it actually was not perfect. Because of that, Spanish uses the indicative.

Very roughly:

• aunque + indicative = although, when the information is real or known
• aunque + subjunctive = even if, when the information is hypothetical, uncertain, or not being presented as fact

Compare:

• Aunque la entrevista no salió perfecta, ... = Although the interview didn’t go perfectly, ...
• Aunque la entrevista no salga perfecta, ... = Even if the interview doesn’t go perfectly, ...

So the indicative here is completely natural.

Because fue fits a completed event better.

• fue gives a judgment about the interview as a whole
• era would sound more like description, background, or an ongoing state

In this sentence, the sister is evaluating the result of one finished event:

• no fue un fracaso = it was not a failure

That is the most natural choice.

A good way to think about it is:

• fue = completed-event judgment
• era = descriptive/background feeling

Because the sister is saying this now, or this is being presented as her current opinion.

The sentence combines:

• a present reporting verb: dice
• a past event inside the clause: no fue

That is very normal in Spanish, just as in English:

• My sister says that it wasn’t a failure

So:

• dice = what she says / her current view
• fue = what happened in the past

If you wanted to place the act of saying in the past too, you could say:

• mi hermana dijo que no fue un fracaso

That would mean my sister said it wasn’t a failure.

Because Spanish normally uses an article in this kind of structure when a noun is used to classify or evaluate something after ser.

So:

• fue un fracaso = it was a failure
• fue un éxito = it was a success
• fue un desastre = it was a disaster

Leaving out un here would sound unnatural.

This is one of those cases where Spanish and English work similarly:

• It was a failure
• Fue un fracaso

Not necessarily.

The sentence creates a contrast:

• it didn’t go perfectly
• but it wasn’t a failure

So the idea is that the interview was probably mixed, imperfect, or not ideal, but still not a disaster.

It suggests something like:

• not perfect
• but not bad enough to call it a failure

So the overall tone is fairly reassuring.

Yes. Spanish allows some flexibility.

The original sentence starts with the concessive idea:

• Aunque la entrevista no salió perfecta, mi hermana dice que no fue un fracaso.

That puts emphasis first on the problem, and then on the more positive conclusion.

You could also say:

• Mi hermana dice que, aunque la entrevista no salió perfecta, no fue un fracaso.

That is also correct.

The original version sounds very natural because it sets up the contrast immediately:

• although X, Y

Yes. Entrevista is a feminine noun:

• la entrevista
• una entrevista
• la entrevista perfecta

So any article and adjective connected to it must be feminine as well.

That is why the sentence has:

• la entrevista
• perfecta

not el entrevista or perfecto.