Question about Unlimited International SMS included in my plan

No, that is not correct. The Perk is only available for use in Canada. It does not apply to anywhere else. https://www.koodomobile.com/en/help/koodos-pick-your-perk-plans

You should still be able to receive incoming text messages for free while abroad. If you do not want to use Easy Roam, you should make sure to include International Voice Roaming to your list of add-ons in your Self-Serve account. If it is not there, we can flag a rep to help you out.