The challenge of translating “quench” is that 1 Thess 5:19 is a famous verse, the normal meaning of the word doesn't fit the biblical context, and the Greek word behind it has an interesting range of meaning.

The default translations work most of the time — like “of” for the genitive. But many times, “of” just doesn't make sense, and that is when you need to check the advanced uses of a case. Here is an example of what is called a “genitive of apposition,” #16.21 in Greek for the Rest of Us.

There are two types of double accusatives. Do you remember what they are?

As a general rule, concordance is a good thing. Concordance is using the same English word for the same Greek word. In Matthew 20:26, the translations correctly translated διάκονος as "servant" and δοῦλος as "slave." But both words refer to the same entity, so why the switch in Greek, and should English likewise switch?

Every once in a while, you will come across a translation that leaves you scratching your head. Why did the translators do that? Where is the Greek to justify the translation? My experience is that this is never a random translation. You may disagree with it, but there is always a reason.