Murphy Crowe starred with a hat-trick of tries in Ireland's 31-0 win over Singapore, while McCarthy also crossed the whitewash on the day and Fitzhenry featured heavily in the scrum half position.
Ireland lost their grip on a 12-0 lead in the Pool D decider against Japan and ended up in the Plate competition, thus denying them a top four finish.
Giving his reaction to IrishRugby.ie, head coach Jon Skurr said: "We're pleased with the progress and the development of the squad. We held our own against Japan, a team that have finished in the top eight in the last two World Series events. A couple of decisions went against us and we ended up losing (27-12).
"I felt against Japan we put a good half together and that's the first time we have played consistently well for a whole half.
"If we had beaten Japan we would have finished in the top four and we would have been delighted with the performance. Instead, we're disappointed because we finished eighth but that is what can happen in Sevens."
The girls in green were using the Hong Kong tournament to warm up for the Guangzhou Sevens, the fourth leg of the IRB Women's Sevens World Series which takes place in China next Saturday and Sunday.
Ireland will have two key players back on board who impressed during last month's tournaments in Atlanta and São Paulo - Munster duo Claire Keohane and Nicole Cronin.
Skurr added: "We will be stronger in China with vice-captain Claire Keohane and influential scrum half Nicole Cronin returning to the squad - both had been rested to allow them to recover from minor strains.
"Our consistency of application will improve with experience and the new caps - Katie, Martina and Amee-Leigh - will add value to the squad.
"The quality of the teams in China is higher than here in Hong Kong and we need to continue to raise our game to meet the challenge of the World Series."
Reflecting on the Hong Kong tournament, the Irish management were left to rue some costly injuries and turnovers during their knockout defeats to Kazakhstan (24-14) and Brazil (20-7).
"Against the Kazakhs we never really got into the game and losing a couple of players to injury early meant it tested the strength of our squad.
"The Kazakhs are very similar to the Russians - big, powerful and direct - and we need to continue to work on our individual skills in order to help the team develop as a whole.
"In the Brazil game we showed more consistency than we did against the Kazakhs. The difference here was that we turned the ball over on three occasions when we had opportunities to score, and teams like Brazil who play regularly in the World Series will punish you which is what happened."