Bartomeu is under fire at Camp Nou after Lionel Messi asked to leave the Blaugrana at the end of a hugely disappointing season.
But Calderon, who previously served as president at rivals Real Madrid, has sympathy for Bartomeu, whose position is up for election in March.
"Being sat in this chair is very difficult," Calderon told Stats Perform News. "It is much more difficult than what people can imagine.
"There are so many critics and yet, when things go well, the praise is for players and managers. It is normal that the president is the black sheep.
"This is the person who is accused of not signing a player or letting a player who fans consider important for the team leave. I don't like it.
"I don't have the information [to properly analyse], but I think Bartomeu has been a good president. From what I see and from what I know of him, I think he is a good president.
"It is very complicated. Even more so in this time when the team start to lose and get that humiliating defeat. The fans don't forgive."
Attempting to explain Bartomeu's actions, Calderon added: "As all presidents do, he has looked for the best for the club.
"Whatever he has done or said, I am sure it has always been for good and trying to get the best for the club he represents."
With Messi now set to leave La Liga behind, Calderon believes the competition will struggle to cope after seeing their two biggest stars depart.
"It would be really hurtful for the image, the quality, the show," he said. "We have been really lucky having Cristiano Ronaldo and Messi playing in our league for the past 10 years, the best two players in the world by far.
"They won't be here anymore, neither of them will be with us. It is really hurtful for our league and for the fans."