I would consider this state as a poor reflection on
Commons' accessibility.
Especially as Google image search (imho, the likeliest
avenue of searching
for images) gives 130 000 pictures of horses on Commons if searched in
English, zero if searched in Estonian ("hobu"), and while it gives 160 000
results for a Hungarian search ("ló") on the first page only one of it is an
image that resembles a horse.
Here's a thought: Enter "hobu" into
translate.google.com, leave
"source language" on automatic and target on "English", and it will
happily translate it into "horse". Could we offer a "translation"
link
in search? As in, "translate my query into English and try again"? I'm
sure we can come to an arrangement with Google (or someone else).