Two practices that are needed for a custom attribute to map into Order Management assuming the

attribute has been created on the necessary objects are:

The types must match within reason. The data type of the custom attribute in Order Management

must match or be compatible with the data type of the corresponding attribute in the external

system, such as B2C Commerce or B2B Commerce. For example, if the attribute is a string in B2C

Commerce, it must also be a string in Order Management.

The names must be an exact match. The name of the custom attribute in Order Management must

be exactly the same as the name of the corresponding attribute in the external system, including

capitalization and punctuation. For example, if the attribute is named “kitItem” in B2C Commerce, it

must also be named “kitItem” in Order Management.

Verified Reference:

https://documentation.b2c.commercecloud.salesforce.com/DOC2/topic/com.demandware.dochelp/

OrderManagement/Administration/AdminAttrMgrCustomAttributes.html