Probably no real impact. I'm not an expert and my knowledge on this comes entirely from a free guided tour of Lisbon I went on today, but the democracy was already a complete disaster. The second paragraph on this wikipedia article[0] says it all:
> The sixteen years of the First Republic saw nine presidents and 44 ministries, and have been described as consisting of "continual anarchy, government corruption, rioting and pillage, assassinations, arbitrary imprisonment and religious persecution".
The linked article actually gives a decent amount of credit to the forgery for the downfall of democracy.
"The revelation of the counterfeiting plot created a huge loss of confidence in the corrupt, democratic government. Military officers who were aggrieved over their pay failing to keep up with inflation, overthrew the democratic government on May 28, 1926. ... A scheme to counterfeit currency and make a forger rich had led, indirectly, to the downfall of a democracy which was followed by a forty-year dictatorship."
As a local, I can't say I trust our History education very much, but when we studied the First Republic, this story wasn't even mentioned. In fact, in 1917 there had already been a coup by an army official/politician, which lasted for only a year until the guy was killed.
> The sixteen years of the First Republic saw nine presidents and 44 ministries, and have been described as consisting of "continual anarchy, government corruption, rioting and pillage, assassinations, arbitrary imprisonment and religious persecution".
[0]: https://en.wikipedia.org/wiki/First_Portuguese_Republic