The lack of an elastic cord in no way affects the tent integrity.
It is also easy to replace either in the field or once back home. You just need to buy some elasticated cord… We supply around 5m of 3mm diameter cord in our pole kits but 2.5mm and 3mm is readily available online or from outdoor retailers.
First remove the old cord and ensure you identify the order that the poles go back together. While not imperative with an Outwell tent you do find that the pole sections can sometimes vary in other models and you also want to make sure that you have the right end poles if you want to avoid rethreading everything.