Hi Zoltan,
Even though most woods darken with age there remains a color contrast that I find pleasing to the eye. The old ship models found in museums were built with local materials and painted or stained to add color. We now have access to several hundred varieties of wood to choose from with a varied color pallet.
I haven’t had any problems mixing different woods. I use the same wood for most structural components and different wood for trim, deck items etc.
Try adding some reddish wood to one of your models and see how well it ages.
Mike