Used the Rodalies multiple times in Barcelone and outside in the suburbs (a lot of stations do have Gates there) this week. Never had an issue finding renfee  staff. They’re also aware of the pass. 

PB has none.

To ENTER a gated station you have to contact counter and show valid pass(day)they then set 1 gate to remote opening.

And how does it work to leave a station? I know there is always a staffed ticket gate in the UK, but in The Netherlands there is not, for example.

If there is no one around you (to open the gate), just walk through behind someone… always works.

In the Netherlands, you can use the mobile QR code to open the gates. For paper passes, the QR code on the pass cover (not the one on the pass itself). You do need a gate that can read QR codes: the ones that have glass plates. If that doesn't work, there is always a pole with an information button. Press it and you'll be in contact with the remote control centre. Tell them you have an international ticket but that the gate doesn't like it. They'll open the gate no questions asked.