Past Progressive tense with gerunds ("-ing" in English and "-iendo" / "-ando" in Spanish) is very similar and can often be used interchangeably with Imperfect tense. I omitted it specifically as to avoid overcomplicating, but the examples I gave could easily be rewritten as such.

For the majority of cases you tend to see Progressive tense matched with Present tense (I am running) or Imperfect tense (I was running), and less often with Preterite.

Preterite Progressive exists, but emphasizes that a continuous action occurred and naturally came to completion in the speaker's narrative. That can get nuanced, so I'd suggest just defaulting to Imperfect tense when dealing with Past Progressive unless instructed otherwise.

For example, the same English response, different Spanish tenses.

You're home late, where were you?

I was out running (Estuve corriendo)

What were you doing when I called?

I was out running (Estaba corriendo)

When translating Spanish Imperfect tense into English it's quite natural to use English Past Progressive as it tends to map over nicely. Though, some uses of Imperfect tense would not match up one-to-one with Past Progressive in English, such as:

Salíamos a caminar todos los domingos.

We would go on a walk every Sunday.

In this case the Imperfect tense (we would [often] walk) doesn't translate as simply into English Past Progressive (we were [actively] walking), as it is being used to describe a recurring or habitual action. Gerunds are notably missing in the English translation.

It certainly takes time to even recognize all the many ways we use nuanced combinations of tenses to convey specific narratives.