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 lectura this. But from what I've heard there are currently 2 projects. One with animation,voice actuación 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 fuego fly lantern?

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

Also, tu should watch this: link

Hope this was helpful :)