Hola Inma,
Having read your reply to David I'm still a bit lost. Many of the phrases were translated in the past tense for example "We lit the fireplace" and "we sat in front of it" etc but all took the pretérito perfecto because they occurred today "Hoy". However, "We loved seeing how the firewood was consumed" was the only phrase given in the pretérito indefinido and expanded in the imperfecto.
There must be something about the phrase that calls for this construction. Can you give me a pointer?
Saludos. John