Cancellation of Registration

One of my clients has applied for GST Cancellation but he doesnt have an arn no. with it.

Now, thereafter Department cancels his registration suo moto.

My query is that,
1. Whether there is any liability arises in future in case i dont want to revoke my cancellation.

2. I have filed my returns upto July. 18 and date of suo moto cancellation is 02.02.2019, so whether there is any liability arises in future for Aug.18 toFeb.19. Is there is any chances of further waiver of late fees so that i can file the returns of remaining tax period

What is the difficulties i have faced at the time of filing of GSTR 9 of 18-19.

Please reply it on urgent basis.

Thanks in Advance.