I agree with all what you have say, but still feel some kind of discomfort with the imperfects here. I think my main problem with the imperfect is that in my native language I have a tense that is very close to the Greek imperfect, and indeed this could be a double-edged weapon, because in many points it is different from the Greek imperfect too. I mean, if I make a literal translation from the imperfect Greek to the imperfect Spanish (which is still irresistible for me, at least in some situations) this would be ungrammatical. May be it is because the aspectual values of both imperfects doesn't match exactly (for example, I don't see that the Spanish imperfect has any inchoative force). However, I am sure I have no a more clear idea of why I use the Spanish imperfect in each particular case neither. So, again, I will try to keep reading without puzzling myself like that, as long as the sense is clear (however I don't promise I will not relapse in this, so thank you for your patience
One of the things that I encounter most confussing is that both verses are grammatically equal, and still they are so different: in the first it is about something that she had being doing since Nausicaa was a child, while in the second there are described actions contemporary with the narration. I would have expected at least an emphatic particle like νύ in the second verse, to mark such difference.
Edit: rereading the whole passage, I think that may be there is a syntactical difference between both verses. I have not posted the context, but the previous verse ends in a "·", so the sentence of the first verse may be coordinated with the previous sentences, which are indeed a disgression that talks about the nurse of Nausicaa. The second verse, instead, is sintactically separated from these sentences, and resumes the narration. Have I found a ring?