When you create Salesforce order and want to be sure it'll be synced to Magento correct you need to follow few rules:
- fill fields in Salesforce required on the Magento side for the Order, use the Order mapping page to take fields relation.
- actually it's: address information, "BillingContact" custom field, Magento Website, BillToContact and ShipToContact fields
- fill fields in Salesforce required on the Magento side for the Customer, use the Contact mapping page to take fields relation
- actually it's: Firstname, Lastname, Address information, phone and email
- order items on the salesforce side should have the same pricebook as assigned to the website in Magento
- fill the "BillingContact" custom field, you may need add it to your Salesforce layout