With async nodes, the states are output via the pins. You have 4 of them here. The first two are of interest to you, i.e. “On Success” and “On Fail”. If you insert a print string after “On Success”, this is triggered after the file has been imported. Keep in mind that the creation of the mesh and the textures then runs via Unreal. It will therefore take some time until the mesh is visible. But the plugin has no influence on this.
Take a look at the “WidgetMesh” blueprint from the demo project.