Fathomfolk mostly takes place above water. It still has underwater scenes, though, so since you're not trying to get hard mode it will still count for the square!
7 Deaths of Evelyn Hardcastle was AMAZING! Do give it at least 100-150 pages before you DNF because the beginning is (intentionally) very confusing. The conclusion was 🤯
Have you read any books by Mercedes Lackey? She's very prolific - her books would fit many of the prompts on this bingo card if you are looking for something! She has books about bards (a whole series in fact), books published in the 90s (and is still publishing currently), and a lot of the others.