Hi unwrittendevin,
You definitely don’t want to change the core files. You can do customizations using a template override, as outlined in our Themer’s Guide.
You can change the text of that button with some customization. However, as outlined in our forum guidelines, we aren’t able to help with these kinds of customizations. But we do have some handy resources that might be helpful for you:
▪ Themer’s Guide – (as mentioned above) provides an overview of how to customize the plugin’s frontend appearance.
▪ Tutorials – useful tips and tricks for changing how the plugin looks and behaves.
▪ Technical Docs – provides an overview of the classes and functions in each plugin
Good luck, and thanks for using The Events Calendar!
~Leah