A workaround I found, while this issue remains unresolved, is to use the REST API to create every localized version. This approach does not overwrite existing data in the original language. When you open it, the ‘Fill with another locale’ button is available. By clicking on it, you can populate the common elements. After that, you can edit the localizable fields with the translations!
Ho to do it:
[https://my.strapi.endpoint]/api/[content-type]/:id/localizations
sending a JSON post as follows:
{ "locale": "es-ES", }