That sounds good, it will be interesting for you to flesh out the requirements and implementation of that and perhaps then look at contributing it back to the Apache Druid project.
One thought is that in the sys.tasks table covers some of your requirements but not all, perhaps extending the schema on that table and adjusting the code the feeds it to add missing columns.
It currently covers the what in `datasource`, the when in the `created_time` field.
It seems like you need `username` and `source_ipaddr` to complete the picture.
I am no expert in the code, but it does seem like the Overlord is the one logging into the table and should be extendable if the missing info is readily available.