There is way to set up a manager user's account so they see another language but the rest see English (or whatever your preference is). Follow these steps:
Security > Manager users
Edit spanish user.
Switch to Settings tab.
Create new setting.
Key: manager_language
Value: es
As of this post Spanish isn't in the standard distribution but can be downloaded here:
https://github.com/modxcms/revolution/tree/release-2.1.0/core/lexicon/es
Thanks for making the effort to describe the terminlogy towards the noobs!