In a correspondance crazyhouse game, the conditional premoves are not working with an @ move. I said this to ProgramFOX on 04/01/2017. So maybe the developers already know this, but it is still not working.
Hmmmm. They may not have heard of your report yet since it's still 01/25/2017 according to my calendar.
Jokes aside, they may already be looking into the process.
Known issue yes, but not currently being worked on. I think about 1% of the games is crazyhouse, even fewer correspondence. Sadly devtime is a scarcity.
github.com/ornicar/lila/issues/1578