Leipzig is also in the Bundesliga not in La Liga and I think you are a little mistaken in this regard and for Stuttgart they just need to maintain their own position until the end of the season by continuing to win in every remaining game. And at least Stuttgart can be in that position in order to enter the Champions League competition next season, because Leipzig is still hindered by Dortmund in terms of fighting for the top four positions in the Bundesliga standings.
In the next match, Stuttgart will meet Heidenheim and in my opinion this will be an easy match for Stuttgart to win at the end of the month, at least Stuttgart needs two wins to take second place from Bayern Munich and I am very confident that Stuttgart is capable of doing that.
We can say that Stuttgart's fixtures were not easy. They will play against both Bayern, Leverkusen and Dortmund in the next month. If they manage to win these matches, they can pass Bayern and get into second place, but I don't think that can happen.
I think Stuttgart played better than expected and managed to stay in the top 3 teams until the end of the season. I think their goal is to maintain their current ranking