Maybe this wasn't the case 8 years ago, but now you can just move the node relative to its local coordinate system...
cubeNode.localTranslate(by: SCNVector3(x: 0.01, y: 0, z: 0)) // Move 1 centimeter along X axis (red)
See: https://developer.apple.com/documentation/scenekit/scnnode/localtranslate(by:)