arywin At this time we have no plans to create an official Spine runtime for the defold engine. so you may want to integrate our spine-c or spine-cpp runtimes yourself. Please see the Spine Runtimes Guide for more information: https://esotericsoftware.com/spine-runtimes-guide
Sorry, I missed the fact that Defold supports animations created or exported in the Spine JSON format. It is better to ask the question in the Defold community as we do not know when the Defold developers will support 4.2.