Simple English sentence component analysis plus translation

I think this sentence is grammatically incorrect.

The common method used to discover extrasolar planets is to find a large number of gas-consuming plants, not their atmosphere.

Used as attributive clauses, relative pronouns and components in sentences.

Which is used as an attributive clause, as a relative adverb, not as a component in the sentence, which=where.

This is the city hosting the Olympic Games.

There is generally no comma before which, which is different from adding a comma before which.

Example 1. The wine in the cellar has gone bad.

All the wine in the cellar went bad.

The wine in the cellar was destroyed.

Wine goes bad in the cellar.

1 sentence means that only some wine has gone bad or it can be presumed that some wine has been put elsewhere.

The wine is probably good.

Obviously, all the wine is in the cellar, and it has gone bad.