Engagement Builder workflow runs can be found in the explore tab:

In this tab, you can see all relevant data connected to what you have setup with the custom workflow function in the Engagement Builder:

The Engagement Builder workflow runs tab has these columns set in the default view:

To see other columns, you can use the columns tab and to filter the results use the filters tabs, CDR refers to the Call detail record ID. The other columns are quite self-explanatory: