The current documentation for spine-godot does not mention support for specular maps. It primarily discusses the integration with Godot's 2D lighting system using normal maps. To use Godot's 2D lighting with Spine, you need to provide normal maps for your texture atlas, but there is no mention of specular maps. As for future plans to add such a feature, the documentation does not provide any information on that.

This is currently not supported by spine-godot. I've created an issue here:
EsotericSoftware/spine-runtimes2835

ram876 My PR adding specular map support to spine-godot was merged this morning on the 4.3-beta branch of the Spine Runtimes. The latest builds of the spine-godot editor and GDExtension should be available soon, so please check them out and let us know if you run into any further issues.