<form th:method = "POST" th:action="@{/validate_regon}" th:object="${numbersList}" modelAttribute="numbers">
    <table>
        <tr>
            <td th:each="number, itemStat : *{numbersList9}">
                <input th:type="number" min="0" max="9" th:size="3" th:maxlength="1" th:field="*{numbersList9[__${itemStat.index}__]}" />
                <span th:each="err : ${#fields.errors('numbersList9[__${itemStat.index}__]')}" th:text="${err}"></span>
            </td>
            <td th:each="number, itemStat: *{numbersList14}">
                <input th:type="number" min="0" max="9" th:size="3" th:maxlength="1" th:field="*{numbersList14[__${itemStat.index}__]}" />
               <span th:each="err : ${#fields.errors('numbersList14[__${itemStat.index}__]')}" th:text="${err}"></span>
            </td>
        </tr>
    </table>
    <button>Sprawdź</button>
</form>