Love it! I too have been toying with reasoning about uncertainty. I took a much less creative approach though and just ran a bunch of geometric brownian motion simulations for my personal finances [0]. My approach has some similarity to yours, though much less general. It displays the (un)certainty over time (using percentile curves), which was my main interest. Also, man, the UI, presentation, explanations: you did a great job, pretty inspiring.

[0] https://dmos62.github.io/personal-financial-growth-simulator...