uses Vanilla 2.0 views (which could lead to incompatibility with other registration related plugins)
cool that you added a plugin, But ...
you based your plugin on an old plugin (mailchimp) that uses vanilla 2.0 views. It lacks events and may be incompatible with other plugins that rely on the events in vanilla 2.1 and beyond during registration process.
Another downside of making plugins that overrides views with vanilla 2.0 views is that their may be security fixes that have been made in 2.1 (and beyond) that are not reflected.
I may not provide the completed solution you might desire, but I do try to provide honest suggestions to help you solve your issue.