1. Czarist Gold is meant to invoke the wealth and glittering iconography of the Imperial Court and Russian Orthodoxy. It's a pretty broad statement but then in 2005 it could be seing as there were only a handful of colours.
2. That creates huge knock on effects to change it now though. If China becomes Gold for the entire period before 1912 (and seeing as we use the two china colours to demonstrate dynastic wars and invasions and the existence of complex rival governments in the warlord era making it an explicitly Imperial colour would necessitate at least 1, maybe 2 more standard Chinese colours), then the colours of Japan and Russia need to change to improve contrast. Japan could go to Red, which would require changing Korea also. Meanwhile changing Russia is what brought about the colour wars, and basically gives us the situation of using Red (which is Soviet), white (obviously not), Black (ditto), Blue (we've already got Sweden, France, Venice, Serbia...) or Green (which contrasts horribly with the Ottomans, hence why I really tend not to use it except for Kerensky's republic in the Civil War). This is without even going into the amount of furore it would create on the forum.
Do you know how many countries are predominately associated with Red, White and/or Blue?
UK, USA, all the Slavic Countries except Bulgaria, Canada, New Zealand, Japan, Argentina, Peru, all of Central America, most of the Caribbean, France, Denmark, Norway, Iceland, Finland, Latvia, most of the Pacific Islands, Korea, the nation of China and, Switzerland and, to a large degree, Russia and Austria (though Black and Gold are also traditional in these areas).
The entire Middle East, Iran and Pakistan are traditionally associated with Green, Black and (to a lesser extent) Red, while all of Sub-Saharan Africa is Red/Yellow/Green/Black. South Africa, India and the Dutch provide a slight relief with Orange, but Purple is pretty much only associated with Imperial Rome/Byzantines (beyond German atlases, but that's getting into a whole different kettle of cultural fish).
And this is the basic problem. By and large neighbouring countries tend to share similar colour associations, whereas what we want is contrast between neighbours.