Based on the information provided in the contexts, it seems that the issues you're encountering with the Blend Tree parameters not influencing Spine Sprite animations in Godot and the peculiar behavior when attempting to change the SpineAnimationTrack Node's Time Scale via code are not directly addressed in the provided documentation. However, I can offer some insights based on the general functionality of Spine in Godot as described in the contexts.
The SpineSprite node and its animation state management are designed to work closely with Spine's runtime and API, allowing for detailed control over animation playback, including time scaling. The method $SpineSprite.get_animation_state().set_time_scale(3.0) directly influences the animation playback speed by adjusting the time scale of the animation state, which is a supported and expected way to control animation speed as per the Spine runtime documentation.
Regarding the SpineAnimationTrack node, the documentation notes that it is experimental and subject to limitations due to Godot's animation engine. This might explain why subsequent attempts to change the time scale property via code are not taking effect as expected. It's also important to note that Spine in Godot has some limitations regarding direct manipulation of runtime objects and properties due to the nature of GDScript and the mapping of the Spine runtime API to GDScript.
Given these considerations, the workaround you've found by directly manipulating the time scale of the SpineSprite's animation state is consistent with the intended use of Spine's API within Godot. For more complex interactions like those intended with the Blend Tree, it might be necessary to rely more heavily on direct manipulation of the Spine runtime objects and their properties, as the integration with Godot's native animation tools (like the AnimationTree and Blend Tree) may not fully support all Spine functionalities due to the experimental nature of some of these integrations.
