When GeoHECRAS starts up, a new, empty project Map View is created using a local coordinate reference system. However, to display external data correctly on the Map View correctly, a projected coordinate reference system should be assigned to the Map View.
A local coordinate reference system is well suited for simple HEC‑RAS models that contain only the HEC‑RAS geometry. Importing an external HEC‑RAS model will cause the imported model to be assigned a local CRS. Similarly, importing any external data without a corresponding coordinate system will cause the data to be assigned a local CRS.
See this article for information on georeferencing an external HEC‑RAS model to a location on the map.