Take a look at the "Simple To-Do list" workflow, which you'll find under Workflows > Examples (at the bottom of the sidebar), you'll see a workflow that essentially does what you have in mind. In this instance, the log being created is a to-do list, but it can easily be repurposed.
To try it out, install the workflow, then type "todo" and the task, e.g. buy bananas. Choose which list you want to add it to and it'll be appended to the relevant text file. Once you've created the lists and added content to them, you can type "vtodo" to view your list.
Based on this, you can either modify that workflow or create your own using the same principle of List Filters to choose which list to add to, and Arg/Vars to store your query.
