Google is getting confused because while the page is ISO-8859-1, some content is loaded into the page in UTF-8. This causes Googlebot to have to re-encode the content page content as UTF-8 so that it can process it. Something is going wrong during that process and characters are getting mangled.
So far i see, french diacritical signs are not a part of ISO-8859-1 (beside of apostrophe). The cache version of Google doesn't contain these characters.
I see two workarounds:
Encode the whole content as UTF-8 (would be the way i prefer)
Encode diacritical signs as HTML entities. Example: séries becomes séries. This can be done in an editor like ...
Thus, instead of displaying >, the article displays >. This occurs (for me, at least) on Chrome, Firefox, and Safari (all latest versions with cache cleared).
That is probably a software error where > was turned into > then that was turned into &gt; by some kind of duplicate encoding. You can use "Control-U" to view the ...
There are five characters that should be escaped as entities in HTML documents, no matter which character set your website uses:
< as <
> as >
& as &
" as "
' as '
Other special characters always can be escaped with entities, but only need to be if you are using a character set that doesn't contain them....