The only thing worth doing is adding a few common international languages

The problem with this, as the article says, is getting the translations right. To convey the message properly. “Shore dump” is currently being translated into Chinese as “beachside rubbish tip”, and “shore break” is being translated into Korean as “shore relaxation”. And many people are already seeing “swim between the flags” as an indication that people doing serious swimming (e.g. swimming laps) are the only ones who should be between the flags.

In Dutch, they have two words for cyclists: fietser (cyclist) for the average person using a bike to get around, and “wielrenner” (literally, “wheel runner”) for people doing cycling as sport. I wonder if a similar language difference might be a problem here with “swim”. We normally use it for anything in the water, but some people are obviously interpreting it as more like the aquatic equivalent of the wielrenner.

It’s not an insurmountable problem, but it is a difficult one.

Plus: most people don’t read signs. So it’s not a bad idea to make the symbols as self-explanatory as possible.