Profile: Paul Bowman

Problem:
The user wanted to display the last commented posts.

Solution:
As you can see in the WordPress database structure, comments are stored in another table than the one for posts. Currently, Toolset does not query/create/update/delete comments. It only acts on the posts and taxonomies tables. https://codex.wordpress.org/Database_Description
There are no shortcodes that will allow you to pull the comments data, either directly, or from posts on a view's query.

I actually did not test the solution, I have suggested on that ticket. You may be right, and "comment_post" is probably not the best hook to use. "transition_comment_status" seems to be a good candidate. This pseudo-code may help:

// Execute this action when a comment is saved
add_action( 'transition_comment_status', 'update_last_comment_field', 10, 3 );
I might also suggest creating a custom shortcode that will return the IDs of the recently commented posts. Check this StackOverflow thread that explains how to get these IDs https://wordpress.stackexchange.com/questions/105534/how-to-get-most-recent-commented-post-above-new-submitted-post-in-wordpress
Then pass the results of this shortcode to a view using an argument:

The view needs to be filtered by the IDs passed in a shortcode argument.

Or you may use a 3rd party plugin such as https://wordpress.org/plugins/basic-recent-commented-posts-widget/

Relevant Documentation:
https://toolset.com/documentation/user-guides/views/passing-arguments-to-views/