Heading Pitch Roll in for 3DTile imorted with Cesium Ion REST API

I’m currently using Cesium Ion REST API to upload my glTF to Cesium Ion with a custom origin (the one defined in blender). The problem was that Cesium Ion automatically defines a new origin for the asset based on the centroid of its boundingbox issue. Using Cesium Ion REST API I can define a custom origin that corresponds to the one I defined on blender. The problem now, is that when I want to rotate my asset using its modelMatrix, the center of the model is now the center of the earth (see this issue. So when I apply a 3 degree rotation, in stead of applying these 3 degrees to my asset relative to my assigned origin, it rotates the asset 3 degrees from the center of the earth (which is huge). Does anyone now how I could use the defined origin and not the center of the earth ? Or is there maybe some way to define a Heading Pitch Roll in the REST API (like the location) since Cesium Ion allows you to modify the HPR ?