This is not possible in the modern version of MySQL Workbench. In fact, there is no way to simulate data - you can upload it only to the server (and not to the model). The only way now is to edit one by one, which is impractical. Even if you rework the data table, the EER model insertion table will be empty. You will notice that right-clicking on the row of the inserts tab gives several options for greyed out, including "load from file". I suspect that the team did not have time to implement them or something like that. Anyway, there is a simple job if you know phpMyAdmin, which seems to handle CSV or MySQL Workbench files well, which I didn't work with CSV files at all.
Decision:
MySQL Workbench, . CSV - Excel CSV - . , , Excel, , Workbench, , - Excel.
, , , .