Brothers Andrei Konchalovsky and Nikita Mikhalkov, Soviet-born directors, said in Cannes on Thursday that they hope for a more liberal attitude in the Soviet film industry under Soviet leader Mikhail S. Gorbachev. Konchalovsky, who has lived in the United States for seven years, added that he was amazed at changes he saw in Soviet culture late last year when he visited Moscow. "I saw hard rock, punk, transvestites on television," said Konchalovsky, who is showing his latest film, "Shy People," at Cannes this year. "I couldn't believe it." But he added that he hopes glasnost, the "opening" proclaimed by Gorbachev, will happen gradually. His brother Mikhalkov--who directed "Oci Ciornie," an Italian production--agreed, adding: "I don't believe in sudden collective enlightenment."