They seem to be missing the incipient disappearance of the -en form of verbs, with people saying things like "I should have went" instead of "I should have gone".

It isn't clear why they feature the constructions they do. They are titled "Yale Grammatical Diversity Project", but the constructions are not necessarily examples of grammatical diversity:

> Have yet to is a construction that appears in most, if not all, varieties of English.

> this construction appears to be distributed across speakers in all regions and demographic groups.

> Repetition clefts are quite widespread in English and can be observed as early as the mid-17th century

> They are robustly attested in contemporary North American English and are also used in the UK. Related constructions have been observed in Australian English (McConvell 2004) and in a corpus of New Zealand English speech as well

> the usage of repetition clefts does not apparently correlate with any sociodemographic features.