Need to allow acronyms with accented characters

There's a preg_match test here that can be updated to allow utf:
http://drupalcode.org/project/abbrfilter.git/blob/refs/heads/7.x-1.x:/ab...

Changing it to use the PCRE_UTF8 modifier, i.e. from
elseif (preg_match('/^[\w][\w\.~\/\-]+$/', $row->abbrs) == FALSE) {
to
elseif (preg_match('/^[\w][\w\.~\/\-]+$/u', $row->abbrs) == FALSE) {
solves the problem but, from a quick reading, I don't think that this works on all platforms.

Maybe it would be better to use the function "drupal_validate_utf8?

The fix has been included in the patch for #2175987: Different abbreviations for different languages.