As I said in another comment the only relevant synthetic language that would refute Chomsky's claim are the ones we have human experiments for. Specifically tho

As I said in another comment the only relevant synthetic language that would refute Chomsky's claim are the ones we have human experiments for. Specifically those of Moro. I believe the relevant papers are referenced here on page 4. (Tettamanti et al., 2002; Musso et al., 2003; Moro, 2016) https://acesin.letras.ufrj.br/wp-content/uploads/2024/02/MoroGrecoCappa_23_Large-languag.pdf https://acesin.letras.ufrj.br/wp-content/uploads/2024/02/Mor...