I am saving error data along the path of my data collection SSIS package into a cache component.
At the end of control flow I'd like to read out all the collected data and direct them into a script component to parse the collected data.
How can I retrieve the data stored in a cache component at a point of control flow execution to process it?
When you say "cache component", do you mean the SSIS Cache Transform transformation, or something else? I've never used it myself, but the documentation for the Cache Transform says that it's intended to be used with the Lookup Transformation, so it isn't a general purpose caching mechanism.
Personally I would write the error data to a regular text file and then parse it. That gives you a persistent copy of the data that can be read by any tool that you like, even outside SSIS.