How about changing some descriptions as well? Complicated words like "cargo" or "express" can be changed to "goods" and "super fast"! Just had an idea. ;)

Nice!!! :) i will try now, in this next version! Thanks

And the rocket needs to be named "up goer" (https://xkcd.com/1133/). :P
"Goods" doesnt seem to be in the most common words list. "Things" or "Items" might be more appropritate.
https://www.ef.com/english-resources/english-vocabulary/top-1000-words/
Though if you intend it to be a learning experience you shouldn't remove everything that looks too complicated.

Hm. Would be nice if it was possible to add custom locales, that way you could add a complete "simple english" locale, which would hopefully be easier to manage than trying to overwrite the normal one. Though that would need a feature request to be implemented :/.

Create a custom locale seems perfect. Thanks for the link, i will start this as soon as i can. I am sharing this worksheet to do something together with some friends, feel free to add suggestions there, will be helpful. At the end we can publish along with this mod, and also perhaps as a mod only of the new language.

https://docs.google.com/spreadsheets/d/1rfr9C7Z2dKP2JyCt7j-0d6j-XwY_bEyJtmgU-ta2-ZY/edit?usp=sharing