Localization: "Manage strings" works only in node's edit form, not in submitted node

Users of Locale/Localizer will be familiar with the "Manage strings" function at admin/settings/locale/string/search , letting you specify any string, and the localized (or otherwise changed) text you'd like it to appear as.

I've found this to work in general, but on one site, I'm trying to localize a custom CCK field name. That is, the field name "Country of Origin" appears in nodes (followed by field content); for Spanish, I'd like the appropriate Spanish phrase to appear instead.

Here's the problem: The Spanish translation does indeed appear as a localized field name, but only on the node's edit form. Once the node is submitted, the field name only appears as the original English; "manage strings" appears to not touch it.

Setup is Localizer 5.x-1.7 on Drupal 5.2. (With this particular site, later versions of Localizer and/or Drupal cause other localization problems to appear!)

In forums, I'm finding plenty of misc. problems people have with localization, but I haven't seen this exact one yet. I have seen indications that user-defined field names simply don't play nice with "manage strings" – though it's curious then that the feature does seem to work when editing a node!

It may be that some localization-related data is hosed on this site, and serious cleaning and upgrading is the answer. But I'd like to ask first: Has anyone else seen this issue, with "manage strings" for a custom field name working only on a node's edit form and not on the submitted node?