Currently, the cross-wiki notifications bundle doesn't list wikis in a useful order (I believe it's alphabetical by DB name). We should list them in order of timestamp, with the wiki where the most recent notification occurred listed first. This applies both to the order of the bundles once expanded, and the order in the text you see before expanding.

This should mitigate T128373: Cross-wiki notifications inform me of very old replies a bit, because wikis with very old notifications would be listed at the bottom.