I don't fully understand your use case. You have a table. Its values come from the Case X [through Report definition]. The table values are editable? In some steps, you want to modify the table values. Then you want changed values go back to the Case X? Please clarify this.

Could you please share the full information about your requirement.

Could you please help me in understanding below sentence ..!

On one of the steps, I change the values in the table and want change them to in case from which I get the values. How can i do this?

I have a [case X], I get a value in the report definition from this case and output them to the table in one of the steps [case Y]. In the next step [case Y] under certain conditions, I have a requirement to be able to change the values in the table and, respectively, in [case X]. [case X] and [case Y] not parent and child. 

If you know the key values of table or some exposed column then you can update by obj methods by opening required row

Yes we can update