I'm not an sub elitist, but in my opinion the argument you can't hear quality in a language you can't understand is over-exaggerated. If you watch enough anime you will get a general idea of what Japanese sounds like. Are there performances that sound fake and terrible to native speakers? Probably, but native speakers don't talk like that anyways. What's important is that it's clear and aesthetically pleasing to you.And the "real fans always go sub!" weeb crowd mostly didn't notice dubs getting better... because they never stopped reading subtitles and pretending they could understand inflection and nuance in a language they couldn't speak.
You can pick up deviations from the norm, so you can tell things like a voice overreacting, being too monotone, or irregular cadences. You can pick up differences in sentence inflections, inflections of common words, or phonemes that appear at the start or end of a sentence that deviate from Standard Japanese. You won't know why, but you'll notice it.
Nuance is, I mean that's there's no way you're going to understand that without having a Japanese literary education. But anime isn't high art, so it's most likely not important.
I only watched the dub a long time ago, but if she forgot the entire journey that's a terrible ending.But then there's also the big change at the end of the movie by adding in her talking with her dad about their move and saying, "I think I can handle it", in the original it's heavily implied that not only did she and her family forget the events of the movie, but that they were essentially reset to how they were before they entered the gate.