I´ve read somewhere, that Dante and some others are working on a Zutara-ending...Does anyone know, if it´s true and when it should be done?

It doesn't really matter since it would non-canon

Not sure if your still pagbaba this. But from what I've heard there are currently 2 projects. One with animation,voice pagganap and more: this one has currently been abandoned. I'm not sure. - Zutara finale project?

Then there is a segundo one that is a simple comic. Its been on hold due to the artists being busy.- The apoy fly lantern?

Just paghahanap up Zutara project on google,it'll lead you to the info that you need :)

Also, you should watch this: link

Hope this was helpful :)