Having rebuilt the whole CB panel (with a slightly higher density, to make room for some new CBs) I found about 7 more of those “not going anywhere” 1/4" terminals shown in post #01.
The wires were labelled and looking up the labels in the Socata wiring manual I see they are power supply wires to the ADF, DME, NAV1, etc. But all those boxes work! So I wonder what those wires do. It looks like somebody had been there (at Socata, or Air Touring) and wired up the supplies using other wires and left these in the harness. Admittedly leaving old wires in place is reasonable (because it takes only a few cable ties in an inaccessible place and you will never be able to pull unused wires out) but it still looks very strange.
One observation which may be relevant is that the 1/4" terminals could push on only onto the white plastic busbars – visible here. But these busbars are the BUS1/BUS2/BUS3 buses before the avionics master, and no way could you power any normal avionics that way because you would blow them up when the starter motor is energised (de-energised, to be more accurate). So I wonder if those wires pre-date the time when the TB series acquired an avionics master switch? The Socata TB wiring diagrams are largely generic and don’t reflect any particular aircraft…
