Switching from Spriter to Spine for your Unity project can offer several advantages, especially in terms of runtime support and features. Spine provides a robust architecture for its runtimes, which are designed to be efficient and flexible, making them well-suited for game development. The Spine runtimes are known for their efficient, easy-to-understand code and are specifically tailored for 2D skeletal animation, which can be a significant improvement over Spriter, especially if you are looking for more advanced animation capabilities and better support. Additionally, Spine's integration with Unity through the spine-unity runtime allows for features like attachment replacement and skin management, which can be beneficial for complex character setups like yours. While transitioning your animations to Spine might be a considerable effort, the enhanced features and support could make it worthwhile for your project.
