How to Account for Inflation

scrail2004​ "Thus, my balance will be worth less, adjusted for inflation, than it is today. Does that make more sense?"

Well, yes. But on the other hand, common sense would have told you that much.

If I might offer an observation, I think a more useful spreadsheet (to the extent you want something that might help in planning or budgeting) would make visible--i.e., in columns dedicated to them--those "assumptions about growth rate, monthly distributions, Roth conversions, taxes, and medicare expense" rather than hiding them behind whatever it was you did to come up with the column B numbers.

The real spreadsheet I have, on which I based my first example for you, is actually something I use to project income and expenses in my retirement years. (I retired 23 years ago (am now in my early 80s.) Both my wife and I have (non-Roth) IRAs, from which we get the Required Minimum Distributions; we both get Social Security payments; occasional, minimal outside income; then we have our various living expenses. Each of these has a column in a spreadsheet; the spreadsheet has one row per year, going into the future; I have assumptions about Cost of living increases (AKA inflation), assumptions about investment growth, in the IRAs, assumptions about annual SocSec changes, etc. That spreadsheet has proven very useful in helping us know how much we need to tighten our belts, or whether or not we can afford a nice vacation trip......

I also have another workbook into which I enter (download) data from banks and credit cards, to track in detail AC:TUAL income and expenses by category.

So it's not clear to me where this spreadsheet you're creating fits into the bigger picture of your own financial planning, but there you have some possible things to consider.