
To my knowledge, CutCopyMode in excel addin is not supported now. You could go to Microsoft 365 Developer Platform Ideas Forum to see if this feature has already been requested or request a new feature.
I would give you two workarounds.
- Set this sheet as protected. If user want to make change, only by your addin. (For the mainly read scenario)
- Clean and re-apply the conditional format manually or periodically. Use
range.clear("Formats")
and apply the conditional format again.
Thanks.