The check for updates is being called on the cron job 'Interface Translation'
If you disable the cron job or disable the "check for updates" on the page you mentioned, there will not be an automatic update on cron runs.
The other methods you name are manually methods.
There is one more method in Core UI, if you translate the interface text manually on the
It also depends on the settings "Import behavior" on the
admin/config/regional/translate/settings page. If the import gets updated.
This is what I know is available in Core UI.
You can of course have other contributed modules as
Drupal Console to update your translations.