The result was delayed after the British team lodged a protest over the part played by a marshal on a jet ski in correcting Beaugrand’s direction during the swim.
Potter would have claimed a second world title had her French rival been disqualified, but had to settle with second place overall after the protest was rejected.
The 32-year-old Briton, who won Olympic bronze at this summer’s Paris Games, put in a late surge to move into the silver-medal position, eventually finishing 12 seconds ahead of France’s Lombardi, who was also third overall.
Fourth-placed Holland, 38, who won the world title in 2018, had only recently returned to the sport after taking time out following the birth of her first child.
“I always said I wanted to come back to a similar level that I was at before having my baby, which was roughly in the top 10,” she said, after claiming fourth on the back of a strong run.
“So I am absolutely delighted with that, it is better than I could have imagined. Back with the big girls for one last time. I am just so happy to be done with that.”
Britain’s Olivia Mathias finished 14th, 2mins 47secs behind winner Beaugrand, with team-mates Jessica Fullagar 16th, Kate Waugh 19th and 2020 world champion Georgia Taylor-Brown in 21st place.
The BBC will have full coverage of the elite men’s race on Sunday, 20 October.