Well, that’s how I feel, too. The difficulty with that phrase stems in part from how to deal with the extra adjectives and syllables needed to convey the full meaning in English. If solterona were as value-neutral as I’d originally thought, then something like “crazy unmarried older woman” would capture it best. But if it’s as dismissive and sexist as Jean says, that’s actually a bit of a relief, because “crazy old maid” is much less of a mouthful.