These two I heard are good alternatives, they work differently but should do the job of tweening animations

I have never used either of them so I can't tell anything about them yet
https://dragonbones.github.io/en/download.html

http://animeeffects.org/en/ - This artist(Chewzers) uses anime effects for example!
They have cool animated art aswell if you wanna see the types of animation you could do with the program