No, the grammar seems right, it's just that there's that massive antecedent phrase. The basic sentence is simply:

The churches of Christ ... shall enjoy in this world a more quiet, peaceable and glorious condition than they have enjoyed.

My use of "sloppy" was addressing its use of "we expect" in a confession of this specificity; the very use of the term, in my mind, introduces ambiguity and uncertainty, not something you want in a confession for the ages.

Did you mean above that this was actually an addition after the full Savoy gathering, or did you mean something else? If the former, do you have documentation?

In Christ,
Paul S