By james art 
Mbeumo hit the post with his first effort but was on target with a second in the 66th minute at Selhurst Park, ruled out after a lengthy VAR review found Eagles captain Mark Gwehi had fouled.
Kevin Schade nodded in the Bees’ second goal but Premier League debutant Romain Esse denied them a clean sheet five minutes from time.
Frank said: “We had (the best penalty taker) before (Ivan Toni) and now we have a second.
“(He has) a very, very good mentality, calmness and focus. I think it’s trust in the process, trust in his strategy, so he did exactly the same thing he does for every single penalty and he knows that’s what he has to do going forward.
“Someone just told me that maybe it won’t ruin his perfect record because he was sent back, so I’m very happy about that.”
Mbeumo’s reprieve means the Cameroon international remains one of just five Premier League players never to have missed from the spot, scoring from all nine of his attempts.
The only better records belong to Chelsea’s Cole Palmer with a perfect dozen, Yaya Toure with an unblemished 11 and Raul Jimenez, who converted 10 from 10, while Dimitar Berbatov also had nine.
Frank expected in-form Palace to be a tough test and was delighted with the way his side came out on top in the wet and windy conditions.
“It’s a big three points,” he added. “I told the players before the game or during the week that this was it, no game defines the season unless you’ve been in a play-off final. We did this twice.
“But I just knew going here to Selhurst Park, it’s very difficult to play here, we haven’t won here (for a long time).
“(We won) against a very good team that I like and admire a lot in very difficult circumstances.
“I think apart from that goal we gave more or less nothing against a very tough and good front three.
“I’m so pleased with a good, solid away performance where I think it’s a fair win in the end.”
New Palace signing Ese scored moments on his Premier League debut when he scored Daniel Munoz’s consolation assist.
The 19-year-old told Sky Sports: “First touch, first goal. That’s the start I’d like to get to and I’m just happy I did it, but I’m concerned about the result and hopefully we can put it right next week.”
Palace boss Oliver Glassner agreed with VAR’s decision to give Mbeumo a second chance and was more annoyed by what he said were four errors in the build-up to the penalty.
While Esse may have offered a glimpse of what Eagles fans can expect, the Austrian admitted it was difficult to fully celebrate the former Millwall winger’s achievement due to the disappointing result.
“We’re all still disappointed,” Glassner added. “Even when Romain started well for us.
“And that will help us gain confidence and integrate, but in the end we lost the game so nobody can be happy today because it’s always a team sport.”