The delimiters are set based on client and server operating systems and can even be different at different UIs in the game, as some stuff is client-controlled and some stuff is server-controlled. We want to switch that over to being controlled by one of these in the future. (Though it's unclear to me if we'd rather use client settings and people probably don't get each other when they chat or do it server sided and people are confused it's not how they're used to it.)
Given you said you're hosting on G-Portal - that's a german provider that will likely use OS settings that make the servers use commas, as you described. Not really anything you could do, unfortunately.