For the record, I don't have any problem to understand the spoken words (by Leslie Caron) in MTT's recording, but the choirs are, indeed, complete gibberish more often than not. I'm not so sure it's entirely Sony's fault here....

Anyway, for the most clarity, my recommendation would be the live recording from 1960 conducted by Inghelbrecht, that has been republished by Naïve a few years back. The CD is... a bit pricey, though.

(Beware, there's also a studio version from five years ealier, with the same conductor, orchestra and narrator, that has been republished by Testament, but its reputation is far from being as good.)