You are losing the forest for the trees.
You've got to back up here. The majority of fans don't understand net present value, inflation, etc. You are getting into specific mechanisms that ultimately determine the exact amounts which will end up making the Net Present Value calculation of a contract off when it's all said on done. But it's confusing enough as it is, no need to further add to that confusion.
And even so, from a fan perspective what you are saying doesn't really matter. They calculate the Net Present Value for CBT tax threshold purposes by using a standard formula that gets applied evenly to every signing at the time of the signing and that's all she wrote for how that contract affects the CBT thresholds.
So yeah, the announced numbers are going to be slightly off compared to the final numbers in the end (though I wouldn't be surprised if the contracts contain provisions that deferral payments are subject to revisions based upon the Consumer Price Index or some other measure), but MLB doesn't care because it's a loose cap and players don't get X% of league revenues. With a hard cap, every dollar matters and can literally prevent teams from doing certain signings and trades. Also, when the players contractually get X% of league revenues you have to pay them exactly that amount or you are in breach of the CBA.
In MLB, they announce the Net Present Value for CBT purposes and the league has collectively agreed that they don't care if that NPV is ultimately off a bit. This is because the soft cap doesn't prevent teams from making moves and it doesn't violate the CBA if the numbers are off slightly either. If they are off, it's just rounding errors on what goes in the league revenue sharing pot and everyone involved has contractually accepted it.
I guess what you are getting at could be getting into the weeds on why deferrals are more beneficial to big spenders rather than small, but whatever concerns there are with that are completely overshadowed by the fact that the small market teams aren't even signing multi-year contracts to begin with. So once again it's missing the forest for the trees.
I've spent way too much time on what feels like billable work but isn't so I'm dipping out of this convo now lol. But to summarize I think it's best to keep it simple and focus only on how this all applies to the CBT thresholds, because that's 99% of the concern.