milankovitch theory is an example of a messy theory, which is the case for most modern theories. what that means is that you can't find nice equations that govern the behaviour of the earth over any period, and you even need to calculate for error and compensate for uncertainty.

so, it's true that the milankovitch theory has proven lacking in key contexts, but the correct takeaway is that the system is proving more complex than we thought it was, and we've yet to uncover all of the complexity. it would be naive to suggest that there's any other way to uncover this besides slowly waiting for the data to come in via increased observation of the relevant celestial mechanics. and, it could take quite a while to work it out.

https://en.wikipedia.org/wiki/Milankovitch_cycles