We can actually use wiki templates to achieve both at the same time. We can have a separate ethics statement page for each journal, where for example the duties of peer reviewers uses this template:
[1]It automatically links to the specific peer reviewers' page for the journal. With these templates we can also change the wording for particular journals, such as saying "patients" in the medical journal and "study subjects" in others, or add entire sentences that only fits a particular journal.
I think we should use such templates generally for the journal, so that any improvement will show up in all journals at the same time.