Customization in WordPress Custom Post Type Archive Plugin

I am using a plugin to display a list of archives on a website.

The existing plugin is called WordPress Custom Post Type Archive. It will display a archives list on the side of WordPress that is based on custom post types. This is a single php file WordPress plugin.

I need this to have the option of sorting the list it creates by a custom post date field. I have two areas of the site that use this, but one of them I would like the archives to be listed based on a custom start date used on a events page where we display archives on the side of the page, so we just need to have the ability to do this as an optional setting and use it for just one area of the site we have used this. If no custom post event start date is available then it would use the default post date instead.