Where Do I Store Data?

Relational Databases a more conservative approach

Text files are not the way to go. Your data is too complex to be effectively and efficiently modelled in a text file. Your model could fit into a NoSQL solution. But the choice to use NoSQL would be entirely personal. I prefer a relational Model with either Mysql (for low cost) or Oracle (for performance). You can have a table for Events, Philosophy, Biography and Parameters and then create crossreference tables between Events and Philosophy, Events and Biography and Events and Parameters. Your model fits perfectly into a Normalized relational model. Your queries will be simple and in a traditional relational database you will never have a shortage of people with the skills to modify the model when modification is needed. Good Luck!