If you're using an out-of-the-box Cost Transparency project with few or no modifications to the model structures (Cost, Budget, Forecast, etc.), then you likely want to route the newly uploaded data to Cost Source Master Data table.
Once the data is there, the table's Expense Type column affects which model each row's Amount value enters:
Expense Type = "OpEx" --> Cost model
Expense Type = "OpEx Budget" --> Budget model
Expense Type = "OpEx Forecast" --> Forecast model