Hmm. I think that the problem might be that these are grouped under the rather generic "Library" group rather than, say, under an "Acquisitions" group.
See config.settings_group; if we added an ('acq', 'Acquisitions') row to that table, then set all of the org unit settings that are prefixed with "acq.*" to the "acq" group rather than "lib", I think we'd be in better shape than going back to the prefixing style of categorizing OUS that we used prior to OU setting groups.
A better description, as Ben suggested, would go a long way too... (See also acq.tmp_callnumber_prefix and others that are similarly obtuse).