Yes of course you can as you will be able to directly contact the host after your booking is completed.
If there is a favorite Japanese dish you love, by trying it at your Nagomi Visit you might discover that there are differences depending on a family recipe, or regional differences. You can also ask your host if you can help cook the dish by expressing how much you love it and want to learn more about it.
Keep in mind that there are certain foods normally served in Japanese restaurants that are not often made at home such as the nigiri sushi which is more commonly eaten at a restaurant or ordered by delivery. Sushi is usually a celebratory meal and if homemade, other types of sushi are made so if you are interested in trying them out ask your host what they usually make.