TypeScript supports a number of languages, however this cannot be set via the tsconfig.json, only via the host environment or the CLI flag --locale. E.g. tsc --locale ru.
Locales supported as of TypeScript 3.7 
| Name | Locale | 
|---|---|
| Brazilian Portuguese | pr-BR | 
| Chinese (Simplified) | zh-TW | 
| Chinese (Traditional) | zh-CN | 
| Czech | cs-CZ | 
| English (US) | en-US | 
| French | fr-FR | 
| German | de-DE | 
| Italian | it-IT | 
| Japanese | ja-JP | 
| Korean | ko-KR | 
| Polish | pl-PL | 
| Russian | ru-RU | 
| Spanish | es-ES | 
| Turkish | tr-TR |