If that's a zsh shell script, you can use the $langinfo special associative array in the zsh/langinfo module:
(that maps to the standard nl_langinfo(RADIXCHAR), see man nl_langinfo on your system for details; $langinfo[THOUSEP] for the thousand separator).
In a bash script (would also work in zsh), you ...
As suggested by jamespharvey20 on IRC, I just changed LC_TIME to another locale. I set it in /etc/locale.conf:
$ cat /etc/locale.conf
I also exported this value of LC_TIME in my shell profile, to avoid having to restart (I couldn't figure out how to get Systemd to reread the locale.conf). This seems a bit hacky but I think it'...