In print_language_string_list function of admin-function.php, the second htmlentities($dbstring) should be htmlentities($dbstring,ENT_COMPAT,getOption("charset")?
if ($textbox) {
echo '<textarea'.$groupid.' name="'.$name.'_'.$locale.'"'.$edit.' cols="'.($short ? TEXTAREA_COLUMNS_SHORT : TEXTAREA_COLUMNS).'" rows="6">'.htmlentities($dbstring,ENT_COMPAT,getOption("charset")).'</textarea>';
} else {
echo '<input'.$groupid.' name="'.$name.'_'.$locale.'" type="text" value="'.htmlentities($dbstring).'" size="'.($short ? TEXT_INPUT_SIZE_SHORT : TEXT_INPUT_SIZE).'" />';
}