...Okay so, I love your idea of Jotaro being able to at least FEEL time manipulation abilities, even if he cannot do anything about them. And I know Ringo is in a totally different universe in a different CENTURY, but it makes me think how would Joot percieve Mandom?
while I don't think Jotaro would be able to feel Ringo through the universes, if he ever did encounter him it would be a bit similar to how things with Kira went.
essentially he'd get an absolutely wild sense of deja vu and a sense of repetition. His memories wouldn't be perfect and he wouldn't know immediately there's a time loop, but there's a sense of familiarity in what's going on which could lead to him putting the pieces together, however given how short the span of time Mandom resets things, it's debatable just how much Jotaro would be able to do about it