How to use the Rules module to lock English nodes from editing? I need to lock all English nodes from editing because translators sometimes change English nodes by mistake instead of creating translations for them. 

Can it be done with Rules? 

I guess it might work with the Rules Condition that uses a data comparison node:language equals English. 

What Rules Action can be used here?
For the event, "a node is updated", use the action "set data value".. Unchanged node's body > Changed node's body and set a site message explaining that the translation wasn't saved.

I'd also make the rule only apply to the translator role.