My question pertains to voting in the West.

I know there is this principle of voting for the greater good of the Muslims. But if we are honest with ourselves, we will see that every candidate here has propositions that clearly contradicts with Islamic principles. So if we vote for a candidate because we think he is the best for the community in general, and then he applies these non-Islamic principles once elected, aren’t we gonna be accountable of that before Allah swt ?
If for example this candidate legalize weed, or extend the maximum delay for abortion, wouldn’t we be considered as partners in the matter?

If this is present in his electoral platform, and there is a fear that it will be applied against Muslims against their will, then it is not permissible to elect him.
But if that was not in his program, but he did it after that, and you were not able to do anything, then you do not have to do anything.