Create JS Function to update JSON file, based on information contained in other JSON files

I Require a function which will read through a folder of files (1 to many) and update their "description" in json, based on their other json values, and with reference to a third json file that contains the options.

I will plug this function into an existing Node.js application

I have included files to explain this further

My max budget is $150AUD for this project (not negotiable)

Preferable if crypto experience for ongoing work on other projects, but not essential