The Argentina attacker struck in the 3-1 win.
Buendia later said: "Just to feel the freedom between the lines and find spaces. The first action I found McGinn with the ball and he scored a beautiful goal.
"Then we have the momentum and we scored quickly. It felt really good coming off from the bench, I try to help the team as much as possible.
"Of course, it is really amazing. First Premier League goal in years, with the injury and a few years I had a few low moments. I worked hard to be back here again so I am really happy."
Skipper John McGinn also said: "Delighted but relieved at the same time. It has been a very poor start to the season. To lose here 3-0 in the last home game was tough to take. We actually started well and then we reacted really well to conceding at the corner.
"It is not an easy place to play when the crowd are on your back but then when you get momentum, what a place it is to play. It was important to show belief and confidence in each other. What a win and what a huge show of character for us."