A correspondent asked me my opinion as to why Shadal defended the wording of the Kedusha barukh kevod versus his emendation berum kevod (as discussed here).
Thinking about it, this was my reply: Shadal was personally very conservative. Even though if we look at him in the light of the past it is clear that in many ways he wasn't traditional, he was totally unaware of that. It was he who came up with the quip, upon hearing of the removal of the yikum purkan by Reformers, that they fulfilled va-yimah et kol ha-yequm (Gen. 7:23). On the other hand, in 1821 the Austrian Emperor required that the Italian Jews under his dominion produce a siddur with translation according to the Italian minhag, and as the editor and translator he was keenly aware of the fluidity of tephillah itself (as well as its rigidity).
In addition, although he believed that text criticism of Nakh was totally permissible and even desirable, like pretty much all traditionalists who took this attitude, it stopped when it came to changing the texts themselves, as opposed to just noting the emendation for the sake of knowledge and truth. His ability to recognize the corruptness of the transmission of (some of) the texts and his need to suggest emendations was driven by his notion of truth, as was his desire to seek out the meaning of the texts according to how they were understood by the original audience. If that didn't mean that how the original audience understood it needs to inform how we understand it, this was so long as we know the difference and do not confuse the two kinds of understandings. Also, this particular emendation was only conjectural. To this day there are no ancient versions, no Dead Sea Scroll fragment which attests to this emendation (berum instead of barukh).
So, to round up, Kedusha might have come from the Navi, but it is not the Navi: it is liturgy. I would not be surprised if he had sensed a corruption in the liturgy on its own terms then he would have advocated emending it; this calls to mind something R. Saul Lieberman said: "There may be one historical truth, but the truth of a text is the truth peculiar to its one literary or oral tradition." (quoted by Dov Zlotnick in his introduction to Greek In Jewish Palestine/ Hellenism in Jewish Palestine, New York: 1994).
In other words, it is the right wording in Kedusha, even if it is not what the Navi said!
PS if you think I'm overdoing the Shadal, you ain't seen nothing yet. Shadalian: coming soon.