Well there are none, as far as my knowledge goes.
But indeed there are other ways.
1) Create a temporary entity a persist able one. While creating a template select that entity and option to create a new row for each excel row processed. In this way after import java action you can retrieve all objects that are currently been imported.
2) If you want to modify the current java action, then I would suggest create a new one which return a list of objects that you need. Then here comes the tricky path. Excel importer uses event based parsing which means that when it encounter a column (while parsing a row) then raises an event and Listener process that column type. Check ExcelRowProcessor class, for meta info, may be from there you can get what you need.
Hope this helps!!
You can add a unique key to a column in Excel that identifies the file. Filter on that key after import. Alternative: use a microflow source that returns such a value that is linked to a user or session and filter afterwards.