Yes there is a way to do this. Just create a table in the name of User account fields having Username, Password and Privilageset. In filemaker just goto menu File>Import record.It will prompt you to choose your file where records are there. After selecting your file a dialouge box will appear where you have to map your fields of file and fields of User Account tables. Just mapped it properly and stop the perform dialouge options,hit import and by this all the records will import into User accounts table. It will hardly take 1 min.
But to filled up 700 account's Username/Password/Privilageset in a spreadsheet is really time taking job.
Once this data is imported, you can then use a script to loop through these records and create the accounts/passwords.