No research has proved that children who like calligraphy have poor mathematical thinking. Calligraphy exercises children's aesthetic taste and hand muscles, while mathematics exercises children's logical thinking ability and problem-solving ability, which are not in conflict and can develop at the same time.
Don't be prejudiced against children who learn calligraphy, or acquiesce in their poor mathematical thinking. These are stereotypes without scientific basis, and children's cognitive development potential is unlimited.