I had some contact with the author, zautrix, a.k.a. Lutz Rogoswki, shortly before he stopped the development. I have discussed many ideas for improvements and also some bugs with him, and he announced new versions, even with better Outlook sync capabilitities. Unfortunately, something made him stop the further development. There must be some new code for Outlook sync in his hands, but he never released it :-(
So my point of view is that developemnt is dead currently.
But hey, it is open source, so everyone is entitled to improve the programs!
daniel