If the Japanese OP is a nursery rhyme, then the ED, "White Narcissus" is a nighttime lullaby. Also performed by Mitsuko Horie, it has her gentle voice alongside Koorogi 73's echoes. It makes for some great Sweet Dreams Fuel.
The OST for "First Night in London" comprises gentle piano and flute music. If you listen closely, you can figure it's a reference to the "Sandybell, Sandybell" lyric in the Japanese ED.
"Encounter with Mother" plays when Sandybell meets the her true mother for the first time. There are no vocals, just beautiful strumming sounds. There is a similar track when Sandybell walks through London, though it has a sadder tone to emphasize her loneliness.
Italian
The dubs of the anime also have amazing theme songs, but special mention should go to the 1983 Italian one by Le Mele Verdi, which opens with what sounds like bells ringing, before devolving into slow, cheerful tunes.
Since the European Portuguese dub was based on the 1983 Italian dub, the theme song sounds similar to Le Mele Verdi's rendition. At the end of the second stanza, the backing instruments start after Susana Menezes sings "O meu nome é Sandybelllllllll!". And again, when she sings "Viva a fantasia, Olá, Sandybell!".
European Spanish
The Catalan Spanish theme song by Maria Carme Ros. In the chorus her voice turns angelic and ends with a Most Wonderful Sound not in the original. The lyrics also add Oliver into it.
The Catalan Spanish ED by Maria Carme Ros is beautiful, but it's also melancholy.
Un jardí somnia ella tenir, veure en ell com hi van creixent les flors, riure i cantar, sentir-se estimada i poder prendre el cel amb les mans obertes. La-la-la-lanote "She dreamed of having a garden, \ seeing the flowers grow in it, \ laughing and singing, feeling loved \ and being able to take the sky with open hands. \ La-la-la-la"
Latin American Spanish
The Latin American Spanish puts a spin on the theme song by having a male singer cover it, imitating Horie's tune despite the different language. Notice the merry rhythym in the back when he says "¡Hola, Hola, Sandybell!" for the first time?