You need to safeguard this info from alteration and hacking and un-authorized access and use.
This is a very broad requirement. In this day and age protecting something 100% from hacking (let alone validating such status) is almost impossible, unless the protection is based on printing out a hard copy and keeping it in a safe + positively destroying (erasing) the source. Creating a "picture" file (by whatever means) is less burdensome but is definitely not "safeguarding the info from alteration and hacking and un-authorized access". Relying on Excel for the above is... a little naive.
In my response to the OP I related to functional validation. Cybersecurity, data protection and the rest are - in my opinion - to be addressed on a more holistic level and not on an application-by-application basis (including validation where and as necessary). My initial assumption was that the spreadsheet is used in this case for more than mere "data capture" / as a "dumb" form - why use a spreadsheet otherwise? One could just use, for example, a Word template or a fillable PDF form. Hence my focus on formulae etc. in that spreadsheet. If all it's used for is recording info by the user, I think that selecting Excel for the task unnecessarily complicates the situation, including the aspects of data protection mentioned above. If this is examined from a more holistic cybersecurity etc. perspective, I'm sure there are ways to make the info much more protectable, upfront.