This question is on how a sentence from Kafka's Amerika (Der Verschollene or Le Disparu) was translated into French. It is from the chapter titled 'Weg Nach Ramses' ('Sur la route de Ramsès' or 'La Marche vers Ramsès').
Da sah er ein paar Schritte vor sich eine ältere, offenbar zum Hotelpersonal gehörige Frau, die lachend mit einem Gaste redete.
Into English it has been translated as follows by Willa and Edwin Muir:
Then a few steps in front of him he saw an elderly woman who clearly belonged to the hotel staff and was talking and laughing with a customer.
In a later translation, by Mark Harman, it goes:
Then a few steps in front of him he saw an older woman, who clearly belonged to the hotel staff, talking and laughing with a guest.
I have also two French translations. The one by Alexandre Vialatte from 1946 gives:
Il aperçut alors à quelques pas de lui une femme d’un certain âge qui faisait certainement partie du personnel et riait avec un client.
Bernard Lortholary's, from 1988, gives:
C’est alors qu’il vit à quelques pas de lui une femme plus très jeune qui faisait manifestement partie du personnel de l’hôtel et qui parlait en riant avec un client.
QUESTION
How can d’un certain âge mean ältere or older or elderly (ignoring the differences between these themselves).
How can plus très jeune mean ältere? Does it need a ne before plus?