Frank Zumbo, who was chief of staff for former federal MP Craig Kelly, had appeals against six indecent assault offences dismissed in the Downing Centre District Court on Wednesday.
He was found guilty of a lesser charge on one other count and had another conviction set aside.
Zumbo was convicted in February 2024 of indecent assaults from 2014 to 2018 against women who worked in Mr Kelly's office.
Zumbo was responsible for hiring staff to work in the electorate office of Mr Kelly, who was the then-Liberal MP for the southern Sydney seat of Hughes.
He was the most senior person in the office when Mr Kelly was absent.
Judge Donna Woodburne dismissed his claims that the four complainants were unreliable in their evidence.
The four women were aged between 19 and 24 at the time of the offending, while Zumbo was more than twice their ages.
The serious accusation that Zumbo exposed his penis to one victim while sitting in a park was found to have been proved.
However, Judge Woodburne downgraded the charge as the victim was not under the authority of Zumbo, as found by the magistrate.
A conviction for indecent assault against a different victim was set aside because there was reasonable doubt she consented to a hug, even if Zumbo "extracted" consent from her, the judge said.
The other charges upheld related to kissing or inappropriate touching on the outside of clothing for short periods.
Zumbo, who wiped his brow repeatedly waiting for the judgment, argued the women manufactured the evidence against him for political reasons.
But Judge Woodburne found the former aide had an "extremely overbearing and demanding personality", and made sexual comments to the women on multiple occasions.
Many of the women stayed working in the electorate office after being assaulted by Zumbo, with one staying "as long as she could bear it" to try and further her career, the judge found.
He will be expected to receive a slight reduction to his original sentence of a two-year intensive corrections order, including 300 hours of community service.
The final sentence is expected to be confirmed on Friday.