In mainnet, bsc will have 21 validators. It will reach finality after 11 blocks not 7 blocks.
Following Parameters should be changed :

1. BlockFetcher: block fetcher will ignore block who's num is before currentNum-maxUncleDist.
2. staleThreshold: miner module will clean works that before currentNum-staleThreshold.
3. miningLogAtDepth: will report finality when one block is miningLogAtDepth before currentNum.