Bit confusing...
Plus Four, is latest CX platform car
A 2005 Trad is a Plus 4
Anyway, don't forget to test with ignition ON as Borghi may have wired the relay to feed only if engine / ign running, to save battery load
Unless I am mistaken and I'm not, the badges on the back of my car say "Plus Four".
That's strange as can be seen below the Plus 4 had matching badge.
![[Linked Image]](https://i.imgur.com/PEB2ynH.jpeg)
Maybe someone retro fitted the CX Plus Four ones?
Regarding your issue it may be the jurys out if Borghi added a bespoke installation. You may have to revert to first principles and trace power feeds. If there is a relay(s) involved it's likely a standalone one.
If I understand correctly you have one fog and one spot lamp. As you suggest the latter should only be allowed to come on with main beam, whereas fog lamps be they front or rear should just require the headlamp function to be selected.