Custom certificate per course on koa.master (native)

On koa.master (native), I have edited the code in /edx/app/edxapp/edx-platform/lms/templates/certificates/_accomplishment-rendering.html to generate the same certificate for all courses. (I did not use template overrides this time).
I am looking for the parameters (variables) of start and end date of each course, so that I can include them in the certificate.
What are these variables?

Note that, I have also tried another way of creating a template for each course from django as shown below, but it did not work. Organization dedicated certificate template - #8 by nadiastef and Open edX certificate template SASS - #4 by giovannicimolin