Firebird SQL data importer on Windows

I have a closed source program on Windows that uses Firebird SQL on its backend. I have the SQL login credentials working and access to the db tables, and I will provide remote desktop access to you. Need you to develop a bulk data import and update utility because the closed source software only allows one entry to be edited at a time and its very slow to update data this way. I would like to be able to bulk load CSV files. Also, binary data (pictures) are imported into the database so you need experience with how to do this as well. The interface should be a windows GUI, not a web app. It needs to preview the data being imported or updated to the user before executing the table loads. I don't really care what language you use to write the software so long as the source is available should we need to modify or tweak it later. You should be familiar with advanced SQL such as left joins or the equivalent in Firebird. One CSV may need to load parts of data into multiple tables. This is a pretty simple project but will require a bit of your time to reverse engineer how the closed source software is importing data to the tables and mimic how it operates. Thanks