Prevent Excel Crashes, Optimize Formulas

I’m working with a multi-sheet workbook whose linked formulas are pushing Excel to breaking point. The file calculates an HRN value on one sheet, then looks up that result (across threshold tables) to return:

• a Risk category and an ENU rating based on where the HRN falls between two limits • a second Risk rating and an Inspection interval drawn from likelihood-and-consequence tables

Right now the logic is hard-wired to specific columns; whenever I insert or reorder columns the references shift, recalculation balloons and the workbook can crash completely.

I need you to refactor these four calculations so the workbook: • stays stable and fast—even with extra columns or column moves • uses well-structured, maintainable formulas (dynamic named ranges, structured references, LET/LAMBDA, INDEX-MATCH, XLOOKUP, whichever is best) • contains clear data validation and friendly error handling to prevent #N/A or circular reference loops

Please start immediately; I must have a functioning, crash-free file ready for review by midday Australian Eastern Standard Time. Budget: AUD 30–250 Skills: Visual Basic, Data Processing, Data Entry, Excel, Excel VBA, Excel Macros, Data Analysis, Data Management