They use that status in many cases even for postal service.
https://www.canadavisa.com/canada-immigration-discussion-board/threads/indian-passport-surrender.771938/post-10638453
Try the above using your OCI application number.
Kids will have there own tracking account but won't see change in status of any activity. The application completes in the end when parents application completes.
Do I even have to provide my marriage certificate? I was previously an Indian citizen. -> If your spouse name is in your Indian passport like I had, you need not give marriage certificate in that case.
eCAS is only available for paper application. It does not work for online ones. You need to use the new tracker for it(https://tracker-suivi.apps.cic.gc.ca/).
They don't explicit mention it but still process such applications. You should understand how controversial it will be if they explicitly mention it on the website.