Hi:
You can edit the package with Reload Editor and republish as SCORM 1.2 but it will only affect the manifest. The runtime functions are different in SCORM 1.2 and SCORM 2004, so you would have to modify them.
Do you know the tool used to create that package? If the package has been created with eXeLearning, the SCORM API will work with both versions of SCORM (1.2 and 2004) and the package can be edited with eXeLearning.