Create a new CTA or reminder, based upon the time an existing CTA has been in a specific status

I imagine you could create a custom date field on the CTA object, and then use a Salesforce Workflow/Process to update it when the Status on the CTA is changed.

Then, you would create a Rule where, in the "Setup Rule" step, you look for CTA records where the Status = "Customer Action" and the date field is a certain number of days ago. I'm not sure, though, if Account ID would be available as a field to draw in. If not, you could create a Data Space based on the CTA object to pull in the Account ID.

Instead of creating a CTA based on that custom date field, of course, you could always take the approach of an Exception Report instead, or even generating a health score metric based on "overdue actions". In our experience, our CSMs have been more responsive to CTAs that fall in the category of "tell me something I don't know", rather than "remind me of something I need to do".