I like how Superman is written here. Judging from his interaction with Firestorm, they don’t seem to have a lot of shared adventures together, with Martin Stein seemingly distrusting him. Not for Superman though, he believes in Firestorm and how he can bring the child back. Any other super hero would just tear in there and beat up Firestorm for what he did in Russia.
And when the kid does turn back into a human? He recognizes Superman immediately, who of course knows how to greet him in Russian.
From – Doomsday Clock #7