So, GOG team could achieve impossible and bring the lost classic back to PC but cannot implement few patches for other, not quite lost, classic?

You either are not even trying or, idk, Capcom/Valve conspiracy?
Just sayin'

The publisher of the game, i.e. Capcom is responsible for patching their game and then asking GOG to forward the update to the servers. Most probably they only care about Steam if there are no freshest patches to this game (I dunno, I don't have it here).