I have found a very nice information about signalling at ffestiniog railway: https://www.festipedia.org.uk/wiki/Signals_Contents
It seems that they used the same signals as sweden in early times - T signal and disc (plate) signal. They were used in combination with staff & ticket, and later with ETS (electric train staff - i.e. token_block in simutrans). Staff & ticket is in essence a sort of time-interval working on one track lines - tickets are given in time intervals, staff governs the direction. So the t-signals should be used with time-interval-with-telegraoph (as an aproximation of staff& ticket), as well as token-block (ETS).
They do not use the term T-singal, but this is what applies: https://www.festipedia.org.uk/wiki/FR_Signals
Each intermediate staff stage station had a centrally located, double-armed, semaphore signal that served as a 'block' Signal. The semaphores acted as a combined Stop and Starter signal, although they did not denote the actual stopping position, they denoted 'Stop and Wait for Train Staff or Train Staff Ticket'; this also applied to the pair of double arm semaphores at Old Dinas Junction at Glan y Pwll. The two arms served up or down trains according to the side of the post.
So I think the T-signal was really used only to signal departure (starter signal). The Ffestiniog railway is a narrow gauge railway - very twisty, deep in forests. In some stations it might be impossible to see the central T-signal from the farthest points, let alone some safe braking distance ahead. (see https://www.festipedia.org.uk/wiki/Tan_y_Bwlch
) For protection of stations, level crossings, tunnels, etc, the disc/plate signal was used. It could be operated remotely (mechanical wire), so it could be put in greater distance from the station building, see https://www.festipedia.org.uk/wiki/Disc_Signals
Also, what I descibed in previous post - a single start signal for the whole line placed ahead of all points - is the case not only for CS/SWE, but also for FR. See the photo at https://www.festipedia.org.uk/wiki/Signals_controlling_section_entry
. There is a normal semaphore at the exit path form station. It was apparently interlocked with ETS - it could be pulled off only if the matching token was put in a drawer slot, and later handed over to the driver of train that was about to depart.
In both arrangements (T-signal, or start signals at both ends), the trains obviously had to stop before Fouling point, in order to keep the switches (and movements on other tracks) clear.
The arrangement with double-block signal, would also solve the problem when a train in token/one-staff mode keeps the reservation backwards up to the signal. If the signal is at each track, the junction is kept blocked, which is a problem if there are multiple lines joining. It would also help with time interval signals where trains are not allowed to go full speed over junctions. Start signal beyond junction would solve that.
A possible (but still partial) coding solution might be what I suggested before - that trains wait for clearance on the platform even if there is a distant signal at platform end, or that they wait for clearance at nearest signal ahead of platform. Even if it is further out than sighting distance, or beyond some switches. However neither of these would work for trains that are not scheduled to stop in the station. That would need the double block signal or T-signal.