A new maintainer of the filter plugin has been announced: Myself.
You can download the bleeding edge from github (https://github.com/eagle00789/RC_Filters/archive/master.zip)
or download the stable version from github (2.1.6)  (https://github.com/eagle00789/RC_Filters/archive/2.1.6.tar.gz) as tar.gz file
The current list of changes in the bleeding edge (2.1.6) version since the original 2.1.2 release by Roberto Zarrelli is as follows:
- Added a notification when the plugin caused 1 or more messages to be moved
 - Make use of some internal structures from roundcube for a config file to keep the plugin compatible with new versions of roundcube
 - Added the first hints of a per filter case sensitivity switch
 - Added a total count to the message when mailes are filtered
 - minor code cleanup
 - Updated english with missing translations
 - Finished the work on the case sensitive per filter option
 
Why are you posting this here?Well, basicly i need your help. I need some translators as i only speak dutch and english myself, i am missing some updated languages.
You can provide them to me by making a fork on github, add the missing translations and create a pull request...