Dear Sir/Madam:
Even though you have not uploaded the files, I still would like to bid. I understand that the project is about improving an existing spreadsheet, the formulas and template are almost complete, but the spreadsheet has to be user-proof and easy to use. The user should only access non-formula cells and should be able to easily understand what and where to input data and not accidentally over-write cells, especially those with formulas. There are other ways of doing it, but the best way is by using VBA. The formulas can be included in the VBA code for it to be completely out of reach by the users, or, the formulas can be placed elsewhere (in a separate, hidden worksheet) and only the VBA code can access it. At the same time, you (and not the user) can change the formula in the hidden worksheet if the need arises without necessarily tinkering with the VBA codes.
Please note that I will never ask questions about Excel formulas. You are right in saying that if I don't understand how the formula works, I have no right to bid on this project!
I'm offering to do this project for you.
Sincerely,
Adina