The reason the Nationalists were able to drive on Toledo so quickly in 1936 was their use of the Madrid-Badajoz railway which passed through the important large town/small city of Talavera del Tajo (Talavera). This important RR is missing from the SCW map thus making it difficult (but not impossible) to replicate the early Nationalist assault on Toledo from the west.
I am not able to post a 1936 map of this here (apparently) but it can be found here:
https://www2.warwick.ac.uk/services/library/mrc/explorefurther/digital/scw/more/maps/
It is the 13th map down with the caption: Map of the area immediately surrounding Madrid, published in The Observer on 4 October 1936. It accompanies an article on 'Gen. Franco's plans for Spain', written at the time of a Nationalist offensive towards Madrid. From the archives of Henry Sara, document reference: 15/3/8/152.
One RR runs south from Madrid through Toledo and on to other points south of there; the other runs through Talavera and on to the Portuguese border. Given the exemplary detail in this project it may be this rail line was intentionally omitted when playtesting indicated an imbalance with Republicans hard-pressed to prevent a Nationalist capture of Madrid from this axis.
But then, that is what almost happened historically.
The supply depot town of Talavera de la Reina on this missing RR should perhaps be a level 4 city as well.