Here it is.
Compacting in formulas - much too complicated... In VBA is easier to detect all consecutive numbers and replace them with: first item - last item. That algorithm for 34f or 56ff looks nice, in the same manner: "21, 22, 23, 24, 25" will be 21ffff ?? I think you are desperately trying to complicate things instead of simplifying
Keep it simple, complicated solutions lead to unexpected errors.
I don't know what to say about how manageable is that way... If you have a lot of array formulas in this workbook, will slow down performance, significantly. Try creating a unique list using a pivot table, this will get updated only at opening, or when refreshing manually.
Catalin