Page translations are not re-indexed when shared meta data is updated on the default translation

The default page translation (the original page) has some meta data that is shared by all page translations:

• attachments
• objects
• page meta data that is duplicated on each translation but that only makes sense on the original translation: hidden flag

In order to be able to search / filter page translations by this shared meta data we index it multiple times, for each page translation. Thus we need to trigger a re-index of all the page translations when this meta data is modified on the original translation.