Importing orders can be do with the flow object.
Example of creating an order:
<objects>
<object type="Customer">
<findOne
for="id"
type="Customer"
identifier="id"
>
<email>test@domain.tld</email>
</findOne>
<email>test@domain.tld</email>
<passwd>*********</passwd> <!-- Il faut surcharge PrestaShop pour pouvoir créer des utilisateurs sans mot de passe -->
<firstname>Test</firstname>
<lastname>Test</lastname>
</object>
<object type="Product">
<findOne
for="id"
type="Product"
identifier="id"
>
<reference>test1</reference>
</findOne>
<name lang="fr">Test</name>
<link_rewrite lang="fr">Test</link_rewrite>
<price>12</price>
<reference>test1</reference>
</object>
<object type="Address" external-reference="test@domain.tld-Test-Test-5 rue du puy-75001-Paris"><!-- Attention, les références externes sont lmimitées à 255 caractères -->
<findOne
for="id_customer"
type="Customer"
identifier="id"
>
<email>test@domain.tld</email>
</findOne>
<findOne
for="id_country"
type="Country"
identifier="id"
>
<iso_code>fr</iso_code>
</findOne>
<firstname>Test</firstname>
<lastname>Test</lastname>
<address1>5 rue du puy</address1>
<address2></address2>
<postcode>75001</postcode>
<city>Paris</city>
<alias>5 rue du puy, 75001 Paris</alias>
</object>
<object type="Address" external-reference="test@domain.tld-Test un-Test-5 rue du puy-75001-Paris"><!-- Attention, les références externes sont lmimitées à 255 caractères -->
<findOne
for="id_customer"
type="Customer"
identifier="id"
>
<email>test@domain.tld</email>
</findOne>
<findOne
for="id_country"
type="Country"
identifier="id"
>
<iso_code>fr</iso_code>
</findOne>
<firstname>Test un</firstname>
<lastname>Test</lastname>
<address1>5 rue du puy</address1>
<address2></address2>
<postcode>75001</postcode>
<city>Paris</city>
<alias>5 rue du puy, 75001 Paris</alias>
</object>
<object type="Order" external-reference="demo-3">
<!--<id_address_delivery>1</id_address_delivery>
<id_address_invoice>1</id_address_invoice>-->
<external_reference for="id_address_delivery" type="Address">test@domain.tld-Test un-Test-5 rue du puy-75001-Paris</external_reference>
<external_reference for="id_address_invoice" type="Address">test@domain.tld-Test-Test-5 rue du puy-75001-Paris</external_reference>
<id_cart>1</id_cart>
<id_currency>1</id_currency>
<id_lang>1</id_lang>
<findOne
for="id_customer"
type="Customer"
identifier="id"
>
<email>test@domain.tld</email>
</findOne>
<id_carrier>1</id_carrier>
<payment>1</payment>
<module>cheque</module>
<total_paid>2.5</total_paid>
<total_paid_real>3.5</total_paid_real>
<total_products>13.5</total_products>
<total_products_wt>10.5</total_products_wt>
<conversion_rate>1</conversion_rate>
<id_shop>1</id_shop>
<current_state>1</current_state>
</object>
<object type="OrderDetail" external-reference="demo-3-1">
<external_reference for="id_order" type="Order">demo-3</external_reference>
<findOne
for="product_id"
type="Product"
identifier="id"
>
<reference>test1</reference>
</findOne>
<product_attribute_id>0</product_attribute_id>
<id_shop>1</id_shop>
<id_warehouse>0</id_warehouse>
<product_price>10</product_price>
<product_name>10</product_name>
<product_quantity>10</product_quantity>
</object>
<object type="OrderHistory">
<external_reference for="id_order" type="Order">demo-3</external_reference>
<id_order_state>1</id_order_state>
</object>
</objects>