The TL;DR on it is without either a hookable event the plugin can catch or adding an explicit log call like the com_privacy models all do (which probably should be done for the CSV export), then there's no way to catch an action to be logged.

For com_cache if I'm not mistaken there's a PR adding logs for that.

So like I ask, would it not be great to add more hookable events for identified "important actions"?

Events are cheap to add, not everything has to be forced into onContent(Before|After)(Save|Delete)

Events are cheap to add, not everything has to be forced into onContent(Before|After)(Save|Delete)

Translation: Go ahead and add events for these important actions and any more that we can identify..

Sorry is there a documentation how to add action log in own component or module or to other 3rd party?

Sorry is there a documentation how to add action log in own component or module or to other 3rd party?

Not that I have seen, all I have seen is the title for that section here: https://docs.joomla.org/J3.x:User_Action_Logs#How_to_hook_an_extension_to_the_system

How to hook an extension to the system

for

check in the checked out items (Important action because allows someone access to something they never had access to before)

see #22530

for

clear the cache in admin as a super admin (Important action because it can literally change a site's output to the world)

see #22739

Not that I have seen, all I have seen is the title for that section here: https://docs.joomla.org/J3.x:User_Action_Logs#How_to_hook_an_extension_to_the_system
How to hook an extension to the system

Thank you @PhilETaylor , but I am dissapointed... How should someone 3rd party prepare for this version if its not documented? How can you expect others to be ready for next version if not written how to get ready? it is always the same for new versions in joomla. you have to know code very well and study it and most time only the persons who implement feature can take advantage.