Just to flag up that the description for the three Bingo achievements is misleading. They suggest that you have to use Unlimited or Standard. However, I unlocked all of them during a single game of Lightning. Naturally, each word that you solve is full length. It does seem kind of silly that the achievements unlock in this mode, so I am guessing that it is a glitch / oversight from the developers. Seeing as Lightning mode helps you by revealing letters, it is not that difficult to get all three of the Bingo achievements here. Will be quicker than using a solver on the web, I think. And you do not have to do twenty rounds of Lightning... you just need to complete twenty words in one Lightning game!
Many thanks to UK Dennis for this wonderful sig!