Since recent betas, Godot forces the game to use the player's locale. In some games this is not wanted so it should be possible to change that behaviour manually but it seems that it is not possible?
Project settings seems to not contain option for that.
TranslationServer.set_locale("en-US") does nothing, no matter what parameter is used.
Setting all controls's LocalizeNumeralSystem to false in a loop will crash the game because of current bug(s) in Godot.
Setting the LocalizeNumeralSystem manually from the editor does nothing.
I managed to find a workaround that may or may not work in all situations. When using C#, it's possible to override locale this way:
CultureInfo ci = new CultureInfo("en-US");
Thread.CurrentThread.CurrentCulture = ci;
Thread.CurrentThread.CurrentUICulture = ci;
But this works only in Mono projects and probably only when inserting values from the code.
So how to set locale so that when a developer for example puts a value 123.45 to a label the value is 123.45 and not something else (like 123,45)?