Sorry. I thought this was relatively well known, so I didn’t see a need to really elaborate (I had actually read the wonderful article before).

Many of our sages hold that the prohibition of meat and milk is connected to nationality, and that we were commanded against the idolatry of the nations who lived around the Land of Israel—as a way of distancing us from the pagan worship that existed. For example, Maimonides in his Guide for the Perplexed, Part III, Chapter 48, Rashba, Ibn Ezra, and others.

In the Wikipedia entry “Meat and Milk” it is brought that this is also the view of Cassuto and Professor Rosenberg (of course they base this on serious arguments and not baseless speculation).

– It may be that the prohibition has a different reason, but we have no way of knowing, and that seems to me the most likely possibility.
– Today, in our reality, there is no one who practices such rituals, so there is no concern that the Jewish people will observe that same pagan rite.
– The Torah is apparently speaking about a norm and not about an eternal fact.

Obviously, a few lines on an internet site are not going to permit the prohibition of meat and milk.
But what are the rules and parameters for such changes or others in the Torah / Jewish law? I assume, of course, that there are none, but I would be happy to receive some general guidelines.

It is still not enough to understand the difficulty. Since there are quite a few Jewish laws for which I do not see a moral or other purpose, the conclusion is that Jewish law has additional purposes. I also do not find it plausible to explain that all of them are meant to uproot idolatry. So such a hypothesis requires substantial grounding, and I am not aware of any (I have not read the materials you mentioned).
But even if we assume that you succeeded in establishing this, and even if we assume that there is no concern whatsoever that the phenomenon of idolatry will return (that is really not necessary), that still does not mean that in our current reality the prohibition is nullified. And that is for two reasons:
1. The explanation that links it to idolatry is not necessarily that it is a fence against idolatry (so that we do not come to worship idols). Sometimes it is prohibited in the same way that idolatry itself is prohibited. For example, I once wrote that this resolves the contradiction in Maimonides at the end of the laws of misuse of consecrated property, where he writes that sacrifices are a decree of Scripture, versus the Guide for the Perplexed, where he writes that they are a fence against idolatry. I argued that it is not a fence, but rather that there is an obligation to direct our religious service to the Holy One, blessed be He, instead of to idolatry. In that formulation, even when there is no idolatry in the world, the obligations of sacrifices remain in force. True, here we are dealing with a prohibition and not an obligation, but similar logic is possible.
2. Regarding the disqualification of women from testimony, I wrote a similar argument for change to the one you suggested, but there it seems clear to us what could disqualify someone from testimony. And since we found no explanation for why women should be disqualified, the most reasonable explanation is that in those days they lacked education and were not involved in public life, and that has now changed. But regarding meat and milk, I doubt how far one can draw such a conclusion, because from the outset it is not clear that we are dealing here with a prohibition that has a clear purpose.

It should be remembered that the accepted view among halakhic decisors is that all Torah prohibitions are not merely fences, but intrinsic prohibitions. In Atvan DeOraita he discusses this at length, examining the issue and bringing opposing examples (very few). That may also explain why we do not generally derive Jewish law from the reason for a verse. What you are suggesting is a clear case of deriving Jewish law from the reason for a verse.

Thank you very much for the detailed answer.