In your Robotics solution, you can use a StringUtils component to split a string. If you have three different fields in your Pega case where you wish to place the corresponding parts of your lengthy string, then you'd simply set each of those fields to a different value once you had split it.
If I am not understanding your issue, please provide more specifics on what you are looking for.
Once the data is returned from RPA to PRPC Capture that value on to single Temporary property and Split the Value using Substring function based on the length and assign that to any parameter. If that is having any special characters based on which you want to split the string there are functions like whatcomesbeforefirst and whatcomesafterlast in String Utilities. These can be used for splitting and assigning the values.