The idea of LANG is that you have it set to your native language in your shell environment (shown with the command "printenv", I guess yours might be unset so it will say "LANG=C" which defaults to English), then it doesn't need to be said on the command line.
If you want to use one language for a particular program and another for everything else, then setting "LANG" at the start like "LANG=tr [program]" is the standard way to do it for any program on Linux. It overrides your usual LANG environment variable.
Adding extra command-line options isn't useful because the current approach is already consistent with most other software. It's not foolish, it makes it clear that you're deliberately overriding the language setting that other software on your system uses.