In order to override a language chosen by the game on startup, we'll need to add a command line option in its properties. Here's how:

1. Right-click on the game in your library, and select Properties. You can access the Properties window of each library item in either of View modes;

classic Small or Large


2. On General tab, click on "Set Launch Options..."



3. In this small window (without quotes or spaces) type "Culture=en" if you want to play in English..



then hit OK and close the properties window.

..or replace en with any one of the language codes from the list below:

• English = en
  
• French = fr
  
• Italian = it
  
• German = de
  
• Spanish-Spain = es
  
• Spanish-Latin America = es-419
  
• Simplified Chinese = zh-Hans
  
• Traditional Chinese = zh-Hant
  
• Korean = ko
  
• Japanese = ja
  
• Polish = pl
  
• Portugese-Brazil = pt-BR
  
• Russian = ru
  
• Turkish = tr
  
• Arabic = ar
  
• Dutch = nl

Now play the game and test it out. For the most part they should be correct, but I cannot guarantee all of them will work, particularly Chinese and Spanish.
I was able to find language codes for both Simplified and Traditional Chinese, as well as two main Spanish variants on this UnrealEngine doc. If you'd like to read more about it, you can do so here https://docs.unrealengine.com/en-us/Gameplay/Localization/Overview

You can use the same launch option for other Unreal Engine 4-based games which released with no language settings. I know there's more out there, but it should work just fine with these:
- ADR1FT
- Shiny (in-game language options are apparently broken)
- Hunting Simulator
- THE QUIET MAN
- Monster Jam Steel Titans
- Stela (duh)


Also, all launch options you set for any item in your Steam library are saved, and persist through install/unistall, until you remove them yourself.
In an event some of the games in question get updated with a language selection menu, be sure to use that and remove aforementioned launch option to avoid conflicts.

Hope this helps a bit.