last untranslatable sentence. Italics ?

The last untranslatable sentence (stating that only the English version of the text will be legally enforceable), given that it will be in a distinct language than the rest of the text, should be emphasized in italics to separate it from the rest of the text.

And any way, I don't see why there could not be a translation of this sentence, that would appear in other languages than English

A simple solution is a code similar to this within the page template:

<translate><!--T:67-->
In cases of conflicting information between a translated version of this page and the original version in the English language,
the English version will take precedence over the translated version.
</translate>

{{#ifeq:{{SUBPAGENAME}}||<!-- do not repeat the untranslated text within the original version -->|''
In cases of conflicting information between a translated version of this page and the original version in the English language,
the English version will take precedence over the translated version.
''}}

This English sentence is part of the template and not to be translated.

You don't understand: I agree that this sentence in English will remain on all pages, but there's no reason why it can't be displayed as well in the actual language of the translation. That's the reason of the suggested #if. Without a translation, the fact that it appears without notice in English will mean nothing to readers, given that they will still not realize that the page is a translation. Look at the code I proposed: this clearly keeps the English sentence within the template, in addition to providing a translation of it just above, at end of the article (and this translation is NOT emphasized in italics, as italics are not convenient in some complex scripts like ideograms).