The fix for JMC-4088 was done by applying the translation when reading page.xml files. This means that the in memory state contains translated strings and consequently also persisted state contains the translated strings. If a user starts JMC with one locale and later starts with another locale, then the persisted strings from the first run will override translations in later runs.
With the current persistence model it is impossible to tell if the user has renamed the pages manually or or if he previously used a different locale.
To reset the translated strings to the new language, the user has to reset the page state, which will also lose any other customizations to the pages.
This is a problem mainly if a user frequently switches between languages.