Dear Sjwi,
Sadly I didn't succeed to set-up a game with "For Whom the Dice Roll" , shame on me !
About the colours used on the nationalist infantry I used Vallejo's Russian Uniform as a base. Mixed with a bit of dark brown for the shade and some flesh tone for the highlights and then a pinch of white in the most raised spots.
The spanish olive green haveoften a brownish hue. Once again, different manufacturers, wear&tear etc you have quite few variations.
Elliesdad,
Bueno's book it's an great source and a must have, but not exempt of errors like the CTV uniforms.
May I add another suggestion? Have a look to the Minairons pdf's , LLuis made an excellent work.
https://minairons.eu/en/114-scw-painting-guidesLook after too the reenactements sites, lots of good pictures and information.
https://primera-linea.es/galeria/Regards