need to filter by a) @ mentions of a user b) all comments by a user .. sorted by date

we have so many tasks that often it is difficult if not impossible to locate a task using current filters.

it would be enormously helpful to be able to show all @ mentions of a specified user  and all comments by a user, sorted by date.  

eg. i know i had asked jill a question using @jill but cannot locate the task.  filtering all @jill and sorted by date would let me find this quickly

eg. i know that john had said something about x y and z but cannot find the task where he said that.  filtering all comments by john, looking at the most recent, would help me find this