The messages say things like "Bashing will stagger your opponent and break their block".
But now many of these messages are not true anymore using my combat mod.

I looked in the string game settings and did not find them. Are these someplace in the CK where they can be easily edited?

I think you're talking about load screens. They have a section in the CK, in miscellaneous.

Yup. They're all Load Screen forms in the object window's miscellaneous branch. You can kill 'em by adding an impossible conditions like 'IsXBox == -1'. They might show once after editing, but won't thereafter.