Isn't the excess supposed to be go into the 'investment fund'? is that still a thing?
I can't help but feel the argument that this is a code limitation is not satisfactory. It is dismissive, pure and simple, because nobody has been bothered to rewrite the code to accept larger numbers. Personally, I have reached this limit on saves in previous versions and was fairly satisfied with the 'investment fund' hack (sorry I mean feature).
Anyway, it really shouldn't matter what percentage of players experience this. The same argument could be made to dismiss countless issues. I will add my vote to this being unacceptable.