As a workaround, I could store and link a new translation with its original one with the following request, which is made from the admin panel when you create a new translation:
async function save(entityName, translation, related) {
await axios({
method: 'POST',
url: `/content-manager/collection-types/api::${entityName}.${entityName}`,
params: {
'plugins[i18n][locale]': translation.locale, // new entity locale
'plugins[i18n][relatedEntityId]': related // original related entity id to link with the new one
},
data: translation, // new entity data
headers: {
Authorization: `Bearer ${auth.getToken()}`
}
});
}
Hope it could be useful for somebody.