Adding @thinspace{} sounds ok to me. I think I agree with using
  and U+200A.
Ommitting a space in Info would be weird for French typography:
As a typographical concept, @thinspace{} should not map to a full space
in text output by default. That would be wrong for everything except
French. If/Since that's preferred for French manuals, then I think the
answer is for such manuals to say something like
@ifinfo
@set punctspace @
@end ifinfo
@ifnotinfo
@set punctspace @thinspace{}
@end ifnotinfo
(Or macros, or whatever.)
Actually, the best answer would be for French manuals to have
punctuation that takes care of its own spacing, but that is a can of
worms.
>
> http://en.wikipedia.org/wiki/Space_%28punctuation%29#Space_characters_and_digital_typography
That page makes a point out of distinguishing a "hair space" around
em-dashes and a "thin space". In practice, I have only ever seen thin
spaces used. I see no reason to worry about hair spaces. I've barely
ever even seen the term.
karl
