What you mean when you ask "I would like to ask if we can manually create a report table with using the Report Table Interface of the Processmaker?"
you can encode data inside the report manually?
If yes, I am sure it is not going to be possible because of Data Integrity. (Check this link https://wiki.processmaker.com/3.1/Data_ ... s#Concepts
) and majority of reporting tool I handle in the past have that feature however, there is one solution if you want to encode data and act as a report and that is by using a PM-Table and I am sure PM-Table can import data from Excel and just edit the data once imported.
If I get your question wrong please leave a reply to further clarify your question.