文字列（複数行）の縦幅に他のフィールド縦幅を合わせる方法（ご質問-追加）

detail.showイベントだとDOM構造が変わり、childrenで各行にtable-cellを適用しているようです。

恐らく以下の形で可能です。

(() => {
    'use strict';
    
    let fieldElement = ['value-5540537', 'value-5540538','value-5540543'];

    kintone.events.on([
        'app.record.detail.show', 'app.record.create.show', 'app.record.edit.show'
    ], (event) => {
        let isDetail = event.type.match(/detail/);

        for (let i = 0; i < fieldElement.length; i++) {
            let textarea = document.getElementsByClassName(fieldElement[i])[0];
            let height = isDetail ? textarea.clientHeight : textarea.firstChild.firstChild.clientHeight;
            let row = textarea.parentNode.parentNode;

            [...row.children].forEach((field) => {
                if (!field.getElementsByClassName('control-value-gaia').length) return;

                [...field.getElementsByClassName('control-value-gaia')[0].children].forEach((el) => {
                    if (el.parentNode.parentNode.className.match('control-multiple_line_text-field-gaia')) return;

                    if (el.className === 'input-text-outer-cybozu') {
                        el.firstChild.style.display = 'table-cell';
                        el.firstChild.style.verticalAlign = 'middle';
                        el.firstChild.style.height = `${height}px`;
                    } else if (el.className === 'userselect-cybozu') {
                        el.parentNode.style.display = 'table-cell';
                        el.parentNode.style.verticalAlign = 'middle';
                        el.parentNode.style.height = `${height}px`;
                    } else if (el.className === 'input-file-cybozu') {
                        el.style.display = 'table-cell';
                        el.style.verticalAlign = 'middle';
                        el.style.height = `${height - 29}px`;
                    } else {
                        el.style.display = 'table-cell';
                        el.style.verticalAlign = 'middle';
                        el.style.height = `${isDetail ? (height - 8): (height - 6)}px`;
                    }
                });
            });
            
            if (isDetail) textarea.firstChild.style.wordBreak = 'break-word';
            
        }

        return event;
    });
})();