They are just exploiting a VALID technicality.
The official prayers for all languages are contained in a Vatican-approved, language-specific missal.
The NEW Lord’s Prayer, as yet, will ONLY appear in the Italian missal. That, obviously, is not what is used in the U.K.
It takes years, if not decades, for the vernacular versions to be translated (from the Latin) and approved by the Vatican. Hence, why there will be a long, long delay before English speaking Catholics will have to re-learn the Lord’s Prayer.
But, rest assured, the pope has the right & authority to change the Lord’s Prayer.