I don't know if the data is reliable enough (I am not a sailor yet…), I am just passing the information ;-)
On the website, they say that “the comparaison with the SHOM are never enormous”…
From what I've see, the prediction are generally less than 10 cm different from the SHOM, the worst I have seen is 40cm different from the SHOM tidetable.
The file is in version 10, so I guess the data are improving with the time.
Anyway, if this source is interesting, maybe the windy team should contact the guy for all the detail (licence, data's updates, etc.)
EDIT: if anyone wants to compare, here are the SHOM tidetable: https://maree.shom.fr/