While working in the Gallery, I think the file browse tool should allow the user to import a file without selecting a sheet or <list of sheet names> as is does locally.
For example, I have created an app in which the user is able to import a file with multiple sheets, and all sheets are brought into separate input data tools with a single file browse tool (shown below).
Since the user does not select a sheet name, the file browse tool only brings in "SelectedFileName.xlsx|". The action tool is then set to replace a specific string "SampleFileName.xlsx|". This allows the input data tools to take this new file name, and add each respective sheet name to the end.
However, when working in the Gallery, the user is required to select a sheet name or list of sheet names, meaning a file browse tool is required for each sheet that you would like to import (shown below). This is a huge inconvenience for the application user, as they have to select the same file numerous times to import every sheet.
Please let me know if you would like me to provide any more information, I would be happy to do so.
Thanks,
Matt