availability reports are not well sorted.
according to the code in report2.php, they should be sorted by host, then by description:

CArrayHelper::sort($triggers, ['host', 'description']);

but there is no "host" field in the trigger array, so the report is only sorted by description.

the trigger array contains a "hosts" array (which in my case always has only one element), that has a "name" field that can be used to sort by host.