Moliere uses rhyming couplets in Tartuffe and each line of the play has the same number of syllables: twelve.
Moliere uses rhyme because this is a madcap, fast-paced comedy, and the rhyme scheme helps both actors and audiences remember the lines, which are spoken in quick succession. The rhyme imposes structure so that the play doesn't become too chaotic.
Translations, of course, can have a hard time replicating this rhyme scheme. It's best to read a work of literature in its original language, but as we all don't have time to learn every language fluently, we are forced to rely on translations. Some English translations try to capture the rhyme as far as possible, while others abandon that attempt and go for replicating the spirit, wit, and meaning of the original without rhyme.