I have not seen a lot of "circumstantial evidence" of Russian interference as you are describing. However that is not to say that there has been none whatsoever

I have not seen a lot of "circumstantial evidence" of Russian interference as you are describing. However that is not to say that there has been none whatsoever and regarding the very close result of the vote this could theoretically have changed the outcome. But in my opinion the main point to your concern is that even if there was some evidence that Russia interfered in the referendum and if there was for example a medium sized probability that this changed the outcome: It should not matter. Elections are a tricky thing because they are _the_ constitutional element of the whole system. If people don't trust the outcome of the voting, there will be no trust in the system as a whole. But trust in the election system is what keeps the whole thing running. Questioning the outcome of a democratic process should therefore only be possible if there is a clear violation, it should only be done by an independent Court and there should be a clear time limit. Considering that the referendum has been held two years ago, that there is circumstantial evidence at best and that it has already immensely shaped British politics, I think it is not reasonable to go back and talk about the validity of the vote. Elections are not a scientific method to determine the true "will of the people". They are an event where people cast there vote and the democratic process gets an outcome to work with. My takeaway from the possible Russian interference would rather be that there have to be measures in the future that prevent meddling and also to prevent the perception that there could have been meddling.