nantokanare I just checked, and of the 900 courses shown on your Memrise profile (https://community-courses.memrise.com/user/nantokanare/courses/learning/), 890 had already been imported. I've just imported the other 10, so all 900 should now be on My Little Word Land! 🙂
Does your dashboard show more than 900 courses? It's possible that Memrise limits the amount of courses on a public profile to 900, or some of courses might be private or unlisted.
My Little Word Land has a way to export your vocabulary from Memrise (https://mylittlewordland.com/import-memrise-progress), but it only supports exporting one course at a time. Do you also have a bunch of courses that you want to migrate your progress for? If so, let me know, and maybe I can come up with a solution 🙂