Messiah

I personally thought that tradition should also have some logic, and here is the question.
As for the substance of the matter, I agree with what you wrote that there should be no individual named Messiah, perhaps this is included in what Maimonides wrote that these things will not be known until He comes.
The necessity to assume this is because intuitively it seems that the gathering of the exiles was done by a group of people (and even heretics, Rabbi), so let's assume that Herzl is the Messiah (as Rabbi Kook said), or let's assume that the gathering of the exiles is all twelve tribes.
And the twelve tribes, when they came to them, were given a milta,
Apparently according to the halacha, it seems that most of the twelve tribes have been true gentiles for a long time (except for the tribe of Dan, where many also believe that they are doubtless gentiles), so one must ask whether the things that depend on the twelve tribes, such as the obligation to pay the tithe and the challah that all of you must pay, and for how many rishonim does a majority of all twelve tribes need, do we have to wait until they convert or are they already out of the tribe count?

I don't know how to say. Simply put, the majority of its inhabitants means the majority of those known as its inhabitants (as Jews).

Perhaps the novelty is that God is the Messiah (not in the flesh) who redeems Israel.

Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord, and he will turn the hearts of the fathers to the children, and the hearts of the children to their fathers.