Its about to be 4 with 1.13 adding almost nothing, and just re-making a ton of textures, it'll be coming up soon. Then they'll need to remake all the textures. I'd just wait to update it 'till 1.13 comes out, there's no point in having animation software that doesn't represent the game its based off of. But even so, I guess you could just put the 1.13 pack into Mine-Imator, yourself. If you want polar bears, I'd recommend using Blender and making your own models or using ones found online. Afterall, Blender is free and can be used for anything you can imagine.