Can use of "fue" or "era" depend on the point of reference?

Question

Hi Inma, I had a thought about V's question below and wanted to check it with you. This applies to statements which don't give any time indicators.

If the speaker is thinking of themselves in the present time, then they will see the past event as complete. "Mi prima fue Miss Universe." In other words, "We're here in the present, and that is a past event which is complete."

However if the speaker is mentally placing themselves in the past, they would say "Mi prima era Miss Universe," as a way of placing you inside the narrative in the past time frame. Kind of like saying, "Let's mentally travel to the past, when my cousin was Miss Univetse."

Hope this is makes senss. If it's correct, it will be a useful concept for me. Thanks.

Accepted Answer

Hola Marcos
I can see your perspective as a valid one too, yes, but not completely. When we use the imperfect to describe how things were in the past it is as you say, as if we put ourselves (our minds) back in the past during that period when that was happening and we see that action "happening" then. 
What I am not 100% sure about is when you say, refering to the preterite, "We're here in the present, and that is a past event which is complete."; I believe we also place ourselves in the past in that case, but we do place ourselves more at that moment when we see that action finished as opposed to being placed in the "process" of that action.
We have a specific lesson on ser in the imperfect vs in the preterite (with no time frames) 
and also have a general contrast lesson. Here they are in case you haven't come across them:
Using Spanish verb ser in the imperfect vs the preterite
Using the imperfect vs the preterite in Spanish (general use)
Gracias y saludos
Inma

Answer

exactly, context the word "fue mi amigo" implies that the individual was once upon a time my friend but is no longer on the other hand i may be thinking of an individual, placing myself in the past, and thinking of the person  who was my friend and may still be my friend but i just have not seen this person in a long time I would say era mi amiga in other words there is no specific time frame when this person ceased from being my friend  as a result my answer would be correct

Answer

exactly, context the word "fue mi amigo" implies that the individual was once upon a time my friend but is no longer on the other hand i may be thinking of an individual, placing myself in the past, and thinking of the person  who was my friend and may still be my friend but i just have not seen this person in a long time I would say era mi amiga in other words there is no specific time frame when this person ceased from being my friend  as a result my answer would be correct

Answer

Hola Sharon
I checked the specific question you came across in your testing. Yes, the sentence would be correct with either fue or era, but in that specific test-question you have a hint saying: 
HINT: Conjugate "ser" in Pretérito indefinido
This means that the only possible correct answer is "fue".
This is why in this occasion it's marked as incorrect.
In test-questions where we are testing conjugation, there is always a hint telling you which tense we want you to conjugate that verb.
I hope this clarifies it for you.
Saludos cordiales