The West "only" needs to produce weapons and deliver them. Ukraine bears the brunt of the war and the casualties.
Nice concept but that convenient (for The West) phase of the war is ending.
The thing about wars is that they have a mind of their own and are rarely as confined as originally intended.
The thing about Western European powers attacking Russia, as NATO is doing more and more overtly every day, is that historically it invariably ends with Russian troops in Western European capitals. The Swedes, Fredrick II, Napoleon, Hitler.
Yes, and there were exceptions such as the Polish occupation of Moscow.
A big difference between your 4 examples and the current war is that these 4 examples were single empires that attacked not only Russia, but simultaneously other European countries (so from the European empire's view it was a 1:n fight). Today most of Europe is in unity with its opposition to Russia (which is a n:1 fight).