Happy that everything works for you now.
It does, the functionality is not exactly the same between the UCI-only wifi-vlan/wifi-station and the file based vlan_file/wpa_psk_file methods. But for a simple, static setup the former is probably easier to set up.
I actually never tried to mix and match, I can see an advantage of using wifi-vlan sections to define the vlans, but then use wpa_psk_file for the actual PSKs. My infrastructure is due for a teardown and rebuild anyway, I might just try that.