If you are creating Component interface by default it will not enforce the prompt values specified on Add search record and will let you input any values even though they are not valid. This is an issue when inserting new rows using ExcelToCI as it allows the user to enter invalid values without giving any error message.
To avoid this issue, open up the Add mode Search record for the component and go to Record field properties for the search fields and check Search Edit check box. This will enforce the use of valid values when adding a new row using Component interface used in ExcelToCI. By default Search Edit is not checked.
Here is the description of this field in PeopleBooks.
Search Edit Enabled only if Search Key is selected. Selecting this option enforces the required property and table edits on the search page. It also enforces these edits under circumstances where the search page would normally be bypassed. With this option, the user no longer has the ability to perform partial searches on this field.
See the Resolution
E-CI: Component Interface Does Not Validate Record Edits (Against Prompt table) When Using Create [ID 664377.1]
If you want the partial search for this field to be enabled, then do the following.
Add the Search field as a read/write property in CI.