Editing custom fields are easy in version 2.0. you need to follow this step shown in figure.

1) Find Custom Fields Column in case of product or orders import. For Product categories choose "WooCommerce Term Meta", For user choose "User Meta".

2) Choose field name for update fields. note that fields name must be meta not title. in case of our example "Product Test " NOT WORK. but "_product_test" WORK.

3) Add New Column and choose your custom Fields name. in our example "_product_test".

4) Fill value for that fields.