There are a couple of really nice CD/DVD compilations (called, imaginatively, Russian Film Music I+II and Russian Film Music III) from Bel Air Music (check out their hideous 90s-look website at http://www.belairmusic.com/BAM%20russian%20film%20&%20sacred%20music.htm) that have got tracks from all these guys and more, plus Tariverdiev as well as the more obvious Prokofiev/Shostakovich/Khachaturian... I first sought them out because I was trying in vain to get hold of Vladimir Dashkevich's Sherlock Holmes soundtrack album.
I (sadly) had to remove Abril from the list, as he passed away recently, but now that it's 2021, I've added 1936 to the list. So far only two composers I came up with for that year - Carl Davis and Klaus Doldinger. Feel free to suggest more, or to otherwise look through the list for updates.
By the way, I can't help but be impressed by that Ray Anthony fella. He's 99 now, 100 next year. And although not a composer, he played on many soundtracks, as previously noted. Here's a video from 2017 - on his 95th birthday - where he does a small gig in a bathroom, of all places:
The "proper" oldest film composers on the list, William Kraft and Johnny Pate, are still going strong at 97.