I have never seen star system used to mean any of those other things

This is a common practice in Russian

It still applies, I think. The term "star system", while technically referring to a system of stars, can also be thought of as the system of objects and interactions governed by the gravitational influence of a star (or stars, in the case of a multi-star system). In the case of single-star systems (e.g. the Sol system), the terms "star system" and "planetary system" will mean nearly the same thing, except that the former would include the system's sun and would also still apply if no planetary system existed.

If we break up the Greek word into its roots

This is a common practice in Russian.

but in English (at least) localization, the above suggestion can be used

If only "system" is used, it doesn't really specify anything. It's left to the context, which is obvious enough.

Can someone explain why the "intergalactic range" tag is unnecessary?

What if there was a feature in Map Mode to exaggerate planet sizes in order to visualize the structure of the stellar system?

Does this also mean it is possible now to increase terrain quality and add more details?

I've made experiments with a logarithmic depth buffer. Results is pretty cool, but there is a lot of work to do. On these screenshots I used astronaut and Discovery model from Doc's 2001 ships pack. Their sizes are real, not exaggerated as Doc originally made. No near plane clipping and no z-fighting.

This will be not enabled in next patch by default, because full supporting of a log Z-buffer requires a lot of changes in the engine. There are two ways of using logarithmic Z-buffer: in a vertex shader and in a pixel shader. First gives artifacts on close or long triangles - their Z value interpolated incorrectly (perspectively). The second method fixes that, but kills FPS to almost zero: SpaceEngine have a huge overdraw on planets, so disabling fast Z test (that required for this method) makes complex planetary surface shader with atmospheric effect to apply to huge amount of pixels.

Anyway, I plan implement a deferred shading pipeline in SpaceEngine, and logarithmic Z-buffer is a first step to it. Deferred pipeline have a lot of benefits: fast Z-pass (that will speedup logarithmic Z buffer in a pixel shader), atmosphere as a post effect (that will speedup it a lot, because there will be no overdraw, and apply it to a planetary surface and ships that are in the atmosphere simultaneously), hundreds of lights (requires for ships at first place), proper lens flare occlusion, and many other.