A typical week-day timetable between December 2020 and May 2021 on the South Wales Main Line. This timetable features the services which ran on April 2, 2021.
The Flying Banana New Measurement Train (1Z20) makes an appearance around 8am entering at Pontyclun, making its way to Swansea, before turning back and exiting via Pontyclun.
Trains coming from Cowbridge Road used Platform 1 on this day, rather than the usual Platform 1A. (for reasons unknown to this author)
Trains between Trostre Steel Works and Margam T.C. are unable to follow the real-life routing, so they are routed via the District Line to/from Margam Knuckle Yard.
A Colas Rail Tamper Machine ran from Shrewsbury to Llanelli and terminated there in real life, however, its next movement is unknown, so it's programmed to run through Llanelli.
A service running 649O terminates at Port Talbot Up Sdgs, however the sim does not provide any routing to this location when writing a timetable. The train instead exits the sim via Briton Ferry Sidings. This service is a Colas Rail Tamper Machine, which is indeed normally housed at Port Talbot Up Sdgs.
A steam train service (1Z30) from Crewe to Carmarthen Sidings failed at Llandeilo station due to "severe wheel flats". This resulted in the severing of services on the Heart of Wales line from 15:55 onwards. The steam train was rescued around 23:00 and brought back to its scheduled destination. (Credit: https://live.rail-record.co.uk/train/?c=U91171&d=02/04/2021) The train on the line behind the failed steam train, 2V12, suffered a near 2.5hr delay at Llandovery - This 2V12 service (Credit: https://live.rail-record.co.uk/train/?c=G97193&d=02/04/2021) eventually made its way to Carmarthen around midnight (Credit: https://live.rail-record.co.uk/train/?c=14488&d=02/04/2021). This is all simulated within this timetable.