Fix and Enhance Excel Workbook for Event Portfolio

I have an existing Microsoft Excel workbook used to manage a 2027 EMEA event portfolio. The workbook currently triggers an Excel warning saying that there is a problem with some content and needs to be repaired... (Budget: €30 - €250 EUR, Jobs: Data Analysis, Data Processing, Excel, Excel Macros, Excel VBA, Microsoft 365, Microsoft Office, Visual Basic)