The Edinburgh Gunners coach guided the national team to a 39-19 win over Romania in Bucharest - almost two weeks after the win over The Barbarians in Aberdeen.
But, after the disastrous reign of Matt Williams which left Scotland with just three wins from 17 Tests, JP believes the feelgood factor has returned to the team. He said: "The players have been down over the last year or so and it is great that Frank has come in and instilled a bit of confidence and a bit of belief.
"I hope things get sorted out over the next few weeks so that we can move on as soon as possible. I hope the Scottish public are back behind us a bit more. There is a lot we can be proud of and a lot we can build on over the next few months."
JP was unable to complete the full game against the Romanians after damaging his ankle after just 26 minutes.
But Scotland interim head coach Hadden believes there is a genuine optimism around the game north of the border.
He said: "There has been tremendous optimism in the game over the past few weeks and, as far as I am concerned, the outlook is bright for the national squad and, as a knock-on effect of that, for the professional teams."
But Hadden was swift to heap praise on his players for their attitude.
He said: "Like me, they were very jaded at the end of a long and hard season, but they have fed off each other.
"Obviously, I was not pleased with the fact that we lost so many points so early in this match, but we kept our composure and stuck to our guns to earn the victory we thoroughly deserved.
"The Romanians were much bigger than us, so we had to move them around and tease open their defence."