Sorry you haven't gotten a response. I will copy this post to the Freightliner forum to see if that gets some responses.
I looked at my power steering reservoir today while the engine was running and, sure nuff, you can see the fluid churning in the reservoir. I would think if it was overfilled, it could certainly splash out of that vent.
2007 Country Coach Allure Siskiyou Summit, sold/traded Nov. 2018.
2019 Grand Designs 384GK-R 5th wheel. Glen Allen, VA