For sure the Austrian GP hasn't been the greatest weekend for Sebastian Vettel, both regarding the raw pace and the German's luck, but there are some positive signs that Seb should put in his bag.

For the entirety of the sessions the #5 has been behind a super Charles Leclerc, with problems also striking at the wrong moments. First his Power Unit problem in Q3 that forced him to start the race in ninth position and then the slow pit stop with the tyres not being ready. About the second episode Ferrari has confirmed an issue with the radio communications that prevented the mechanics from being warned on time about Vettel coming to the pits, which costed the German three seconds in a tight battle with Lewis Hamilton.
This unfortunate situation with any chance has prevented Vettel from reaching what would have been a great podium finish. Indeed the run down to the finish line against Valtteri Bottas could have easly been tured in Sebastian favor without that circumstance.

"I'm driving a great car" aknowledges Vettel "of course I'm disappointed with what happened to me yesterday [qualifying issue] and with Charles' result. He has been really strong thoughout the whole weekend and he would have deserved the win. Still this one has been a great GP for us, possibly as much as the canadian one".

https://www.motorlat.com/notas/f1/11850/verstappen-039-s-philosophy-has-been-the-winning-one

Speaking of the parallelism between Austria and Canada tho, a warning signal appears: Ferrari has proven to be very competitive when it comes down to engine-rewarding tracks such as Spielberg, Montreal and Sakhir but for different reasons the Scuderia is still winless after nine races.
Reliability issues for Charles Leclerc and a spin for Sebastian in Bahrain, the penalty in Canada, bad luck and an outstanding Max Verstappen in Austia have been key factors that kept the Maranello team away from the top step of the podium, while Mercedes in its worse weekend so far still managed to get a third place. That's alarming for the Scuderia since engine-frindly circuits are becoming less and less with the championship going on. The best chance of winning for the Ferraris will probably come in Monza, which would be a romantic eventuality for a maiden victory in the 2019 season. But that won't be enough. The most successful team in the history of Formula 1 and the runner-up of the 2018 World Championship just cannot settle for a single win in a year. Something has to be done quickly. 

Were the strong performances in Austria only due to the powerful engine or did the upgrades finally work as well?
We'll just have to wait and see in Silverstone that on paper shouldn't suit the most famous red car in the world.