Expense & Misc Transaction Obj are not available in List of Standard Objects in Application Composer

Summary:

We have a requirement to auto populate the project and task number on selecting/changing the  DFF LOV field(which contains concat of  WorkOrderType-SubType~Project-Task~Legal Entity) in Expense and Miscellaneous Transaction. We tried to edit the DFF field but it is not allowing us to edit. Now we are planning to achieve the requirement using Groovy script, But when we open Application Composer none of the objects of Expense and Miscellaneous Transaction are appearing . My question is , Expense and Miscellaneous Transaction is available with app composure to write any groovy script? If yes, am I missing any specific role? OR