Currently, the Spine plugin cannot be upgraded to use UE5's skeleton and animation system. The integration of Spine with Unreal Engine's skeletal mesh system is not straightforward due to the differences in how Spine and Unreal Engine handle skeletal animations. The Spine runtime does everything from skinning to vertex deformations, which would interfere with Unreal Engine's skeletal mesh system. Therefore, physical animations and sequencer animations in Unreal Engine cannot be simply implemented by running Spine skeletal animation components inside the SkeletonMeshComponent.
For more details, you can refer to the spine-ue4 Runtime Documentation.
