I live in mediterranean scrub. Tempratures rarely (if ever) get above 40°c, that's why scrub plants don't die in summer. Tempratures generally go between 15°c-35°c, and are around 25°c most of the year.
I agree about the steppe grassland, which is unlike anything in the game.
I know what you mean, I do study meteorology and climatology in university. The problem here is, non of the temperatures in the game actually reflects real life averages, it's not an issue with scrub in particular. Most other biomes experience this problem in a much larger scale, like tropical biome.
Mediterranean summers are in fact hotter than equatorial savannahs of Africa, but even those in the game are constantly over 40 degrees. That's just a game mechanic that affects all regions of the world. So even if the scrub map uses the same temperatures, it will actually be more "realistic" and closer to averages than what it is for african savannahs. We can use weather station data to compare.
The temperature range will be 16-42 degrees which will be fine, the only problem being it won't have a winter pattern with occasional single digit temperatures.