I am a bit surprised about the number of 'unknowns' in the data for my mother toungue (Dutch) [1]. Are these still open questions with respect to the Dutch language or is it simply that no expert on Dutch grammar has been asked to contribute.<p>[1] <a href="https://grambank.clld.org/languages/dutc1256" rel="nofollow">https://grambank.clld.org/languages/dutc1256</a>
"What shapes the structure of languages? In a new study, an international team of researchers reports that grammatical structure is highly flexible across languages, shaped by common ancestry, constraints on cognition and usage, and language contact. The study used the Grambank database, which contains data on grammatical structures in over 2400 languages."