I would say that the Icinga2 Livestatus is not compatible with Multisite Livestatus anymore.
The problem is not the protocol or communication directly. It is more the different tables and columns.
Multisite is expecting some columns not available inside the Icinga2 Livestatus.
In your case it is the column
The bug or better feature request should go to Icinga2 to add this column.
If you want to connect different Livestatus backends, there are not many possibilities. I would try if this is possible with Thruk and the Livestatus Multi Daemon.
From Thruk Documentation
LMD fixes some issues in backend specific livestatus implementations, ex.: Icinga 2
One question - is there a special reason to use Icinga2 with CMK Multisite?