Hello,
Thanks for reaching out! If you’re using your theme’s page template on the event category pages, then you would need to customize that template via a child theme to load a different sidebar depending on the event category (our functions list has some functions that you can use to check if you are on an events page and to check the event category). Alternatively, you could use the default events page template (under Events > Settings > Events template) and do a template override of that, which you can find at wp-content/plugins/the-events-calendar/src/views/default-template.php.
We are limited in the amount of support that we can provide for customizations, but if you get stuck or have any questions, please let me know – I’ll be happy to point you in the right direction!
Thanks,
Jennifer