Is excel C populated automatically from excel B? I don’t really understand the relation there.
Either way, you can use excel’s read cell activity to read the information from excel B/C. Do this for all variables you will need. Then use the excel write cell activity to write all of the variables into excel A.
I see there are userforms being used though instead of just cells. RPA does not do well with things that aren’t simple sheets. They don’t interact with objects, active x controls, and userforms very well in my experience. To be honest this seems to be entirely within excel and is likely more suited to VBA