To edit event descriptions, dates and times and include additional notes in PDF exports you click on the event settings icon. This is located in the top right hand corner of the builder and opens a sidebar with options.
In the sidebar there is a summary of the objects and props in the plan along with the event name and description which are editable.
Clicking on the edit button allows you to add information or include date & times for your event which is included in the PDF export.
Details added into these text boxes are included in the PDF exports. The additional notes are displayed on the last page of a PDF export.