I would have to do a lot more reading up on it to comment more thoroughly. Several things do come to mind, though. While the LLX is a translation from the original language that renders that word (that you reference, Ekklesia), I would think that one would want to go to the original language for a more thorough understanding of what was being said originally.
Now, for the New Testament, it was written in Greek, so that would be legitimate. For the Old Testament, I would want to hear how some of those language scholars compare the original language to the Greek version. And then, one would want to get into things like context and to whom it was written and so on.
The other initial thought that I had was that this would tend to mix up the distinction between the Jews and the Church, as the Bible speaks to these different groups and in different ways. If the Jews are the Church and the Church is the equivalent (or maybe a superset of the Jews) — then that would seem to play into Replacement Theology, in that the Church has assumed all the promises of God, which were given to the Jews (i.e., national Israel) and Israel has forfeited their rights and/or promises (to the Church).
Anyway, these are not really developed thoughts but only initial ones and I would have to go further into it and see where it leads. If it leads to the wrong places, then there would definitely be something wrong with it.
That remains to be seen...
shalom b'SHEM Yah'shua HaMashiach Adonai
Very specifically: Romans 11 where Paul discusses who is grafted into whom.
NAsbU Romans 11:17 But if some of the branches were broken off,
and you, being a wild olive, were grafted in among them
and became partaker with them of the rich root of the olive tree,
NAsbU Romans 11:19 You will say then, "Branches were broken off
so that I might be grafted in."
Paul warns against the pride of a Gentile follower of Yah'shua.
NAsbU Romans 11:22 Behold then the kindness and severity of God;
to those who fell, severity, but to you, God's kindness,
if you continue in His kindness; otherwise you also will be cut off.
NAsbU Romans 11:23 And they also, if they do not continue in their unbelief,
will be grafted in, for God is able to graft them in again.
A Jew who comes to know the Jewish Messiah for their salvation
does not become a Christian,
They become a "called out one", a member of the Ekklesia.
They become a Messianic Jew.
The L-rd's name ( Shem ) is not je-zeus;
it is Yah'shua ( YHvH is my salvation )
NAsbU Romans 10:13 for "WHOEVER WILL CALL ON THE NAME OF THE LORD WILL BE SAVED."
Which is why you must call on His Name for salvation.