Odoo country list was mapped to the InvoiceXpress names as documented at
https://invoicexpress.com/api-v2/documentation/appendix

These InvoiceXpress country names found no macth in Odoo:

Burma
Canton and Enderbury Islands
Dronning Maud Land
East Timor
International Monetary Fund
Ivory Coast
Johnston Island
Kampuchea
Midway Islands
Netherlands Antilles
Samoa (America)
Tahiti
Upper Volta
Vatican
Wake Island
Western Samoa
Zaïre

These Odoo countries found no match in the InvoiceXpress list:

id,name
base.aq,Antarctica
base.bq,Bonaire, Sint Eustatius and Saba
base.bv,Bouvet Island
base.tf,French Southern Territories
base.va,Holy See (Vatican City State)
base.xk,Kosovo
base.bl,Saint Barthélémy
base.mf,Saint Martin (French part)
base.pm,Saint Pierre and Miquelon
base.sx,Sint Maarten (Dutch part)
base.gs,South Georgia and the South Sandwich Islands
base.ss,South Sudan
base.tk,Tokelau
base.to,Tonga
base.um,USA Minor Outlying Islands
base.vi,Virgin Islands (USA)
base.ax,Åland Islands
