Automated would be nice but is likely to fail no matter how automated and super easy.
Can he handle situations when things go amiss or just simply wrong? Even with respect to basic computer skills for email, internet, online streaming, etc...
Seniors are very vulnerable. Would he recognize a financial scam?
Start out with a good paper system for organizing and filing. Determine if that is manageable to begin with....
Then, since you apparently have some vested interest, you do the data entry and reporting every so often - monthly I would expect.
Give that a try and smooth the process out as necessary. "Teach and train" as you go along. Hand-off when he is ready and able.
And not likely to be calling you with every little glitch and mis-step of any sort.
But keep a close eye on his finances. If some large expense is made and/or the system breaks down you could be in for a financially bad surprise.
Or what if he simply makes some error of omission or commission? Enters in the big property tax bill and forgets to mail the check.
Mostly playing "devils advocate" here. Many 80+ seniors are quite capable.
That can change very quickly. Or sometimes even worse - very slowly......
Guard against a false sense of security - the spreadsheet/app is there but going all wrong.
Not a lawyer (full disclosure) and truly do not know the circumstances and relationships that you are working with.
However, I do know that, when it comes to seniors (and actually everyone) and finances, be sure to set up the applicable legal documents: e.g., will, power of attorney, etc..
Beforehand.
Just my thoughts on the matter.