This is the reason why we should never redraw lines on a map over historical claims. It gets messy fast.
Moscow, and future tsarist Imperial Russia, happened much later
This is wrong on so many levels :)
In times of Kievan Rus Moscow was a far province of forests and marches. Kyiv was the capital.
What you're saying basically: "Italy (Ukraine) was always owned by France (Russia) because Roman Empire (Kievan Rus) was the first centralized state there".
If you insist on applying modern names to historical states it was the other way around - Ukraine "owned" Russia back then.
Also for a few centuries Ukraine was owned by Mongols, Lithuanians and Poles. And Russia was only starting to exist (and wasn't called Russia at first - just Muscovy). But that's besides the point.
Is it wrong? I don't know, is it wrong to call the Sun cold, or the Universe small? Maybe not. Googling "russian ukraine" will not result with articles about Ukraine, it will result with news about the war between Russia and Ukraine.
Can you point to some respectable sources that use the term "Russian Ukraine"?
russia and ukraine are tied and its not offensive or wrong to say something like "russian ukraine"