Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.102.0
• OS Version: Linux (latest Chrome)

Steps to Reproduce:

1. Open VS Code for the Web.
2. Edit the setting TypeScript: Locale. Select an option other than "auto" or "en" like below.
   
3. Create a new text file. Switch the language to TypeScript. Type some nonsense and wait until a red wiggle appears.
4. Read the diagnostic message. It is still in English. The locale settings is ignored.
   

Expected

On Desktop version, the locale option is respected.