The tourists were in the ascendancy throughout at the National Stadium in Karachi, having posted 556-9 in the first innings before bowling hosts Pakistan out for just 148.
Cummins opted to bat again as opposed to enforcing the follow-on for Babar Azam's Pakistan, who were set a mammoth 506 to win or to bat just under two days to secure the draw.
Led by captain Babar, who batted over 10 hours for his 425-ball 196, Pakistan decided on the latter option and their star batter was aided by Abdullah Shafique (96) and Mohammad Rizwan (104 not out).
Nathan Lyon spurred Australia to battle until the end with two wickets in two balls, dismissing Faheem Ashraf and Sajid Khan, but Pakistan held on for a famous draw.
It could have been a different result, though, given Steve Smith shelled Shafique late on day four and Usman Khawaja dropped Rizwan with three overs of play remaining on day five.
"I think the positive thing is each time we've created more than 10 chances," Cummins said. "It's probably the disappointing thing this game as well.
"If we took a couple of those catches it might be a different scenario. I walked off the field at the end of the day's play without feeling there was something I hadn't tried, or there wasn't a plan we hadn't given a really good chance at.
"In foreign conditions, we are showing that we are able to adapt and play well over here. But of course, getting so close, [being] so far ahead of the game, and not coming away with the result can feel like it's a missed opportunity."
Debutant Swepson finished with figures of 0-156 in the second innings from his 53.4 overs, but Cummins heaped praise on the spinner, along with his partner Nathan Lyon.
"I thought Swepo bowled fantastically," Cummins said. "I don't know how he's ended up with those figures. Especially that middle session, he had an umpire's call, a couple of half-chances dropped off his bowling, lots of plays and misses.
"The way he was able to be a real wicket-taking option on a really good wicket without really footmarks to the right-handers I was just really impressed with how he went about it.
"Nathan, I thought he bowled well, particularly today. Felt like he was going to get a wicket every over. When I took off him to bowl Starcy or myself, it was a hard decision to make because felt like he was so close to a wicket all day."
Asked whether he left enough time to win the Test, leaving five-and-a-half sessions to dismiss Pakistan, Cummins responded: "Overall I wouldn't change too much to do honest.
"Batting into day three gave us that chance to really have a crack at them – probably went better than we could have expected – but over here the wickets are pretty good.
"We tried to bat two-and-a-half days on the best time of the wicket, hoping that it would break up on day four and five and it held together pretty well.
"Babar, Rizwan, Shafique, thought they all batted fantastically the last two days. We knew the wicket wasn't playing too many tricks but they batted superbly and made it really hard to get that breakthrough and when we did the next guy stuck at it as well.
"The good thing is it's nil-all, we didn't lose anything. Coming over here in these conditions, at the start of the series if you'd said it was going to be nil-all after two games you'd probably take that."
Australia will look to seal a series victory in the winner-takes-all decider that starts in Lahore on Monday.