As of now, Ren'Py does not have official support for Spine. The focus has been on getting the Spine 4.2 release out and addressing other runtime updates.
For GameMaker Studio 2 (GMS2), the developers are working on updating the runtime to the latest Spine version, so you might see improvements soon. However, if you are looking for an engine that supports Spine 4.2 and is easier to use than Unity or Unreal, you might consider engines like Phaser, which has good support for Spine features when using the WebGL renderer. Another option could be Cocos2d-x, which also has robust support for Spine.
For more information on supported engines, you can refer to the Spine Runtimes documentation.
