“God works all things for good” is unfalsifiable. If good comes of a tragedy, God did it; if nothing does, the good is hidden or future. A claim compatible with every outcome explains nothing.

This is a fair point about how the verse is often used. Romans 8:28 is not an empirical prediction to be tested case by case; it is a promise whose truth depends on the whole Christian story being true: God exists, the resurrection happened, a renewal is coming. It is falsifiable in the sense that Christianity is. If Christ was not raised, Paul says, the faith is worthless and the promise with it. Read this as a promise inside the Christian framework, not as evidence for the framework, and it does its real work.