I wonder why the vent is even needed for the cylinder. My old Direct Lift, which is identical, ever had that. Wouldn’t the fluid naturally push back into the reservoir as the lift lowers? That’s the only part I don’t like about this lift. Might I ask what you paid for the lift and jacks?
I think it just helps keep air out of the oil/gives it an easier path to escape so there don't have to worry about running out of stroke on the cylinder before the lift is all the way up. Might just be overkill or for when first filling could help.
I have same model, but Revolution (rotary) RFP9. No vent hose but the cap on the pump is a vented cap. This one seems like it is not vented but has the hose.