Tagged as "Resolved"
Ask Me synchronicity ... 18 years later: In 2006, ninazer0 asked for help identifying three works of English Juvenile Historical Fiction, later finding the answer to one of the mystery texts. In 2024, tangerine asked about mid-century kids' historical fiction about the Hanseatic League, and paduasoy's suggestion was not the author OP was looking for, but it did resolve the earlier mystery. Then melisande added more info for the earlier question. Delightful!