Alexander Prass put the visitors ahead in the seventh minute, finishing Tim Lemperle's pass after Hoffenheim caught Palace on the break. Dean Henderson then kept the Eagles in the contest with an important save from Andrej Kramaric.
Palace pushed for an equaliser and created opportunities of their own, but their task became harder when Wharton was sent off in the 77th minute after receiving a second yellow card.
However, the hosts refused to give up. Kamada struck in the first minute of added time, turning home after Tyrick Mitchell had headed the ball into his path to secure a valuable point.
Sage admitted that conceding so early had made the evening difficult for his team.
"With this scenario, by conceding early in the game it was difficult because we had to push to come back," he said.
"We created chances and they created too. Dean Henderson kept us in the game, that's why it's difficult to say it's 100 percent on our side or their side, but with this save he kept us in the game and we scored at the end.
"I think the players deserved it, because they didn't give up, and that's the main thing I want to keep this evening."
The Crystal Palace manager felt there had been an improvement in attacking performance compared with their previous matches, but admitted his team still needed to find a better defensive balance.
"Offensively we did better as you know than our two previous games," he said.
"We have to continue to improve defensively because we gave too much space to the opponent. We are sometimes in difficulty in 1v1s, in duels, and that's why they created these kind of chances."
Sage acknowledged the challenge of balancing defensive security with attacking ambition.
"When we defend too much we have no chance to exist in the game, and when we try to attack, we are quickly open. What is difficult for us is to find the balance between the two things."
He believes keeping possession will be central to improving Palace's performances.
"That's why I think the best way for this team is to keep the ball, and to keep the ball with efficiency, and this evening we showed that too."
Despite being reduced to 10 men, Palace continued to push until the final whistle.
"What is important in this situation is to stay alive and to push – and we pushed until the end and created chances," Sage added.
"What is important is to keep in mind that we tried all the game to come back, and at the end we came back, and we had maybe the chance to have more."