The Manchester United loanee featured in Saturday's Champions League final defeat to Real Madrid.
Terzic said, "The last six months, Jadon has been brilliant for us. Of course, it took him some time to get back into shape. But you could feel his quality was going to help our game, his first touch. He improved himself and those around him.
"I didn't speak about the future because we've been speaking about the present. I am really happy that he is with us. Playing in a final in his hometown, it's a very special moment for him.
"You can feel the joy he receives and brings in the dressing room. I am very happy to work with Jadon. We don't know yet what the future will bring. But for sure, it's going to bring him another Champions League final."
On defeat at Wembley, he also said: "It's quite hard to analyse the last 12 months, but I do think we have had a season with a lot of ups and downs. We've had too many changes and lot of games that didn't go our way. Today is a perfect example of what is possible with this team, what we can achieve.
"There was a big disappointment in the group and staff (in the dressing room). What is really good is that we showed from the first whistle that we were here not to play a final but to win a final. That's why it's mixed feelings.
"It was also the final game of the season. There are players that are going to leave the team and leave the club."