Thank you for your helpful comments, also for Bryan's further comment.
Just to clarify things, I was not trying to suggest a perfect
correspondence, rather that the differences were not great and that it
might be instructive to examine them. It still seems to me that for
non-stative verbs the difference is small: simple past and wayyiqtol
are generally sequential but can be used (though perhaps not
preferred) for past within past; whereas the preferred form for past
within past is past perfect and X-qatal. One more difference is that
in Hebrew X-qatal is continued with wayyiqtol, whereas English
continues with past perfect.