Word Replacements accessing legacy field that has no UI
When an older install has translations in the field civicrm_domain.locale_custom_strings, it can really confuse.
Based on the last time this code was touched (https://github.com/civicrm/civicrm-core/commit/234d8f09414678e7b8e94cada91637de1f89e582) I'd think it's high time to get rid of that field?