I know I'm late to this question, but I see that none of the answers really address the question of "nuance."
You could go your whole Esperanto life without having to fuss too much about the word olda, but as far as evitindaj neologisms go, olda has fairly strong roots. There are almost 5% as many references to oldulo in the Tekstaro as references to maljunulo, and a similar proportion between oldulino and maljunulino. (Note that many references simply to old- or olda are discussions about the word, and so should not be counted.)
Generally olda has to do chronological age (and so could be seen as similar to maljuna) but there are rare references to newness, especially in compounds such as "oldtestamenta" and "la oldgreka".
As has been mentioned elsewhere, olda is generally found in song and poetry, but it does find itself used in general contexts as well. Often, but not always, it means exactly maljuna. It's clear, however, that the intended meaning of oldulo is not always the same as maljunulo. To some, it takes the emphasis off of loss of youth and therefore is a kinder thing to say. To others, it seems to suggest "stuck in ones ways" or "fuddy duddy" rather than mere age.
In the context you provided (the translation of Alice in Wonderland) I would conclude that the author simply meant maljuna (the original is "old woman") and chose olda for one of many possible reasons - including breaking up what would have been a clunky sequence of three-syllable words: neniam fariĝi maljuna virino