Localized LUA Dissector tostring() in TShark Output

I have a bunch of Wireshark LUA dissectors which populate tree contents by using LUAs tostring() method. There are places where I output double with tostring(). Now tostring() seems to use some kind of locale to determine the decimal splitter to use for doubles. On my windows host machine, which is german, I get commas in TSharks output and in a linux guest machine I get dots in TSharks output for doubles. Obviously because of the locale.

Now my thought was that I just have to change Wiresharks/TSharks locale/language. From the Wireshark UI this is no problem (Edit > Settings bla bla ...) but I'm unable to set the locale for TShark by e. g. using the following command line "$ tshark -o language:??? ...". TShark throws an error which states that the flag "language" is unknown. I even can't find a corresponding setting by calling "$ tshark -G currentprefs".

Is it even possible to set TSharks locale by command line and when... how?