Collection error while trying to add and update in excel

Im trying to automate formatting an excel. I did it using automation for excel and it takes a lot of time.
Things I wanted to do-

  1. if there are multiple values separated by comma i.e - abc, efg, hij in one cell, it has to be like this(insert in subsequent cells)
    and the cell with comma has to be deleted
    Then again same process if there are cells with comma and values.
  2. Changing a complete column of text case to title case
  3. Inserting empty cells with value like hello/hi

The automation i wrote opens and closes excel file 3 times for each of this process and consumes time.
can some one help me how to do it in less time.

i have attached the file created for reference.
Output_file.xlsx (19.0 KB)
FormatExcel.xaml (22.3 KB)