[ModelicaSystem] fix filename for model based on imported FMU

Author: syntron

OMPython/ModelicaSystem.py

@@ -1670,7 +1670,7 @@ def convertFmu2Mo(
             raise ModelicaSystemError(f"Missing FMU file: {fmu_path.as_posix()}")
 
         filename = self._requestApi(apiName='importFMU', entity=fmu_path.as_posix())
-        filepath = self._session.omcpath(filename)
+        filepath = self.getWorkDirectory() / filename
 
         # report proper error message
         if not filepath.is_file():