[Django]-Django-CMS multi-regional and multilingual subsite

I’m not sure how flexible you are with your URL scheme, but how about this:

Use the standard django CMS i18n URL rules (so you end up with yoursite.com/ja/ and yoursite.com/en/).

Next create two pages: ‘au’ and ‘jp’. Redirect the homepage to one of the two pages (or write some smarter logic for that, for example in a middleware). Now keep your regional content in those two sub trees.

Simply don’t translate the pages in the ‘au’ subtree into Japanese if you don’t want.

You may make it, by writing your own copy of i18n_patterns.

So by definition:

Language prefix in URL patterns

i18n_patterns(*urls, prefix_default_language=True)[source]

This function can be used in a root URLconf and Django will
automatically prepend the current active language code to all URL
patterns defined within i18n_patterns().

Here an example made inside template but same variables/objects you need in your implementation.

Reversing in templates

If localized URLs get reversed in templates they always use the
current language. To link to a URL in another language use the
language template tag. It enables the given language in the enclosed
template section:

{% load i18n %}

{% get_available_languages as languages %}

{% trans "View this category in:" %}
{% for lang_code, lang_name in languages %}
    {% language lang_code %}
    <a href="{% url 'category' slug=category.slug %}">{{ lang_name }}</a>
    {% endlanguage %}
{% endfor %}

The language tag expects the language code as the only argument.

Reference: Django docs – i18n/translation