Currently 'Replace' is a primary action, present in the template part block toolbar, while 'Edit' is hidden away in the ellipsis menu:

In most cases it's more likely that you'd want to edit the selected template part, so that should be the primary action. Replacing should be secondary.

Suggested revision:

There may even be an argument that having the Edit button in the toolbar is too prominent since you can already directly manipulate the template part contents. But since the toolbar has very few actions, I think it might be ok to try, especially as focus mode may be the preferred editing mode for some users.