You can't send an email based off basket plan id because a basket isn't tied to a specific plan. A basket can have several plans, promotions applied, taxes applied, etc.. That information is a part of the baskets items list, which that information isn't available from CB Auto Actions.

The most reliable way to act on plan state change is the below usage.

Plan Active
Triggers: onCPayUserStateChange
User: Automatic
Access: Everybody
Conditional 1: [var3] Equal To PLAN_ID_HERE
Conditional 2: [var2] Equal To A

Plan Expired
Triggers: onCPayUserStateChange
User: Automatic
Access: Everybody
Conditional 1: [var3] Equal To PLAN_ID_HERE
Conditional 2: [var2] Equal To X

The plan emails are using the above trigger (CBSubs Email is at least).

Probably onCPayAfterPaymentStatusUpdateEvent checking that status is Completed or Processed. That's the trigger used for all of our tracking plugins (idev, piwik, and google), but you'd really need to use it in a custom plugin to utilize it best as it has several function calls for the basket to retrieve more detailed information that's probably important for your invoice (e.g. access to totalizers, basket items, etc..). Otherwise just use the above triggers, the presentation tab emails, or CBSubs Emails if you don't need detailed basket information.