macos – What allows/prevents altering language for a given software?

In idea, I can configure (through the system preferences) any software to run below a particular language (totally different from the default system langauge).

Nonetheless, for some functions this selection is disabled and macOS tells me, that the appliance …

would not assist further languages.

e.g.:

So: How does macOS decide that an software helps further languages or not?

I am on the lookout for a low-level clarification (past “contact the builders of the appliance to repair it”), as I am the developer of this particular software (which is cross platform, and my native OS is not macOS – therefore my ignorance) and wish to add assist for choosing languages.