Already had some bad experiences with people testing my Grist tables and destroying some formulas by typeing over them.
You could deny editors schema edits in the access rules page. The default rules would be edited like this:
The S represents schema edits which are 1) edits to the structure of the document (creating or deleting tables and columns, for example), 2) edits to the layout (pages and widgets), and 3) formulas. By denying editors schema edits, they cannot edit formulas, but they can update data within the document you created (e.g. data entry and exploring data within your structure).
Note that in columns with trigger formulas, Editors would be able to modify the calculated value, but not the trigger formula itself.