First : thanks very much for this great plugin which helps me a lot.
So I'm French and I use accentuated characters in hashtags. The original regex couldn't match with those hashtags, so I've tweaked it a bit.
Regex is situated in : /[your_plugin_directory]/wp-twitter-widget.php at line 451 – in public function linkHashtags().
Just replace the preg_replace_callback() regex :
by this one :
I'm not a programmer so I suppose this code isn't very nice and smart but I does the job for me.
I hope it will help someone as it helped me. :-)