Taking the straight path towards the middle of the dimension, Aldrin had prepared himself to encounter numerous dimensional creatures.
It's not something new considering he had that experience in the Small Insect Colony. Being swarmed was already ingrained in his mind so his mind was fully at ease in assessing the situation and reacting accordingly.
However, that's not the same for Irina. She was a simple descendant of an Energy Refiner Lineage. She received guidance, and training and in the end, awakened as an Energy Refiner. She trained once more in the camp but her first real battle against the dimensional creatures was during the attack of the green-spotted hyenas. Even then, her role was limited.