Automated static timestamp WITHOUT Macros (Long shot maybe?)

Hello,

My spreadsheet exists as a single-use calculator workbook on an online documentation system. Users are required to download a fresh copy from the system every time they use it and it and paste their data into it, but sometimes they will re-use a previously downloaded copy by deleting the old data and pasting in the new data. This increases the risk of errors and I want to try and discourage this without the use of macros, because of time constraints (I know this can easily be done with a simple macro but I have a deadline to validate the spreadsheet by and the use of any macros requires extra validation steps, which are time consuming).

I realise this is a long shot but can anyone think of a way this could be prevented or at least traced, without the use of macros? Just anything which could indicate when the spreadsheet was downloaded, or when data was first pasted in, so I can run a quick check to make sure that a fresh version was used.

I've included a sample of the spreadsheet anyways but some info here: the data which users paste is in a very predictable fomat, so certain cells will always be blank and certain cells will always contain "1", for example. The spreadsheet actually does not perform its calculations unless all these conditions are met, as this indicates that the data has been copied/pasted incorrectly. Also the entire spreadseet apart from the yellow data entry regions will be locked for editing by users.

P.S. if it's not possible without macros and you are able to, please provide the macro which you would use to achieve this, so I can at least present options and try and wangle a deadline extension if needed!

Thanks in advance!

Phoebe