My insight: Putting critical lenses on CPH (Critical Period Hypothesis)
Is there a magic period to start learning a foreign language? This theory was initially based on L1 learning and has found its place in foreign language learning later. But that is all water under the bridge now. Under favorable conditions, the gap is closing except for a few issues including phonology and pronunciation. We may also claim that more mature learners can learn a foreign language faster at least at the onset of language learning trajectory when it comes to grammar and lexical components with their advanced cognitive and analytical abilities.