No excuses for Garmin's failure to make the required changes to their little sync utility.
It's been 4 years. All other Mac apps with a few exceptions have done it, apps that are much bigger much more complex much better than any of Garmin's little utilities, they did it within a few months.
No, installing Rosetta is not the solution. It's a bandaid.
Tell your software team to do something instead of nothing. It does not take 4 YEARS to do this.