On Save Hooks and displaying a custom message

[presswizards]

I am using the Admin Options framework, and considering the full version for Customizer etc.

For the Admin Options, I came across an "After Save" hook, but I don't see a way to have it also display a custom message, and the documentation is very light on those hooks. Can you point out how to display a custom message at the top, like a normal Admin Notice, when I hook in to "After Save" and run a function, and then display a message from that function?

Specifically:

csf_{$prefix}_save_after or csf_{$prefix}_saved hooks

and

csf_{$prefix}_save filter

Also, details on how to use csf_welcome_page, csf_dev_mode, csf_{$prefix}_output_css, etc. Providing example code for these in the docs would go a long way towards helping developers or their managers justify a purchase request or decision, when the documentation is very good and complete. Thanks so much.