We are using content approval and now we would like to change the pending status to checked.Is it possible to change ModerationStatus (draft, pending, approved, rejected) to (draft, checked, approved, rejected)?
This is technically impossible. The status value may appear as a text but it is internally stored as
SPModerationStatusType enum (with a fixed list of values) which are mapped to their resource strings to be displayed localized on the UI.
You could provide your custom UI (forms, pages) for the user which would show different texts than stored in the moderation status. You could als develop a custom workflow based on your own field with the desired values. I find the two options rather expensive providing that the status values otherwise suit you well.