As Hebrew words do not correspond exactly to English words, there can not be just one "correct" translation. This is especially true with proper names.
Therefore both "Nahal Ayalon" and "Ayalon Stream" are equally valid.
Whilst "Ayalon Stream" is the more user-friendly translation, "Nahal Ayalon" better reproduces the flavour of the original.
That is why I reverted name:en to its previous value of "Nahal Ayalon", and set "Ayalon Stream" as an alternative in tag name:en1.