Could smaller battleships ease the Soviet construction problem?

Would the Soviet Union have been better off building treaty-sized battleships instead of the Sovetsky Soyuz class?

Probably, although the larger problem was the long interruption in battleship construction before the new programme.

Treaty-sized battleships are considered a probable improvement over the Sovetsky Soyuz programme. Soviet yards had gone so long without building battleships that even a smaller project faced a difficult restart. Reducing the design's ambition would not remove that interruption in experience.