Based on this documentation, https://developers.arcgis.com/qt/spatial-and-data-analysis/spatial-references/#datum-transformations, ArcGIS Runtime only contains a small number of transformations out of the box. To get more specific and less widely used transformations, the user needs to install the projection engine data separately and set the transformation catalog path. This gives access to the more specific ones such as what is referenced in this defect.
Step 1: Download PE Data as described in https://github.com/Esri/arcgis-runtime-samples-qt/tree/master/ArcGISRuntimeSDKQt_QMLSamples/Geometry/ListTransformations#additional-information.
Step 2: Add the following line to the code to set the directory in ArcGIS Runtime; 'Component.onCompleted: TransformationCatalog.projectionEngineDirectory = file:///Users/luca6804/ArcGIS/Runtime/Data/PEDataRuntime'