TYPO3 Core

i used the CKEditor (Be) for my own Extension, with Flexforms. And make dots in me setting arguments e.g.

<settings.description>
<TCEforms>
<exclude>1</exclude>
<label>Beschreibung</label>
<config>
<type>text</type>
<rows>5</rows>
<cols>30</cols>
<eval>trim</eval>
</config>
<defaultExtras>richtext[]:rte_transform[mode=ts_css]</defaultExtras>
</TCEforms>
</settings.description>

then i got the following error Message

index.php?route=%2Frecord%2Fedit&token=d0ec8fb…&edit[tt_content][39…:245 Uncaught TypeError: Cannot read property 'description' of undefined at index.php?route=%2Frecord%2Fedit&token=d0ec8fb…&edit[tt_content][39…:245
...

The problem is:

require(["ckeditor"], function(CKEDITOR) {

...
       require(['TYPO3/CMS/Backend/FormEngine'], function(FormEngine) {
             CKEDITOR.instances.data_tt_content__39__pi_flexform__data__general__lDEF__settings.description__vDEF_.on('change', function() {
                 CKEDITOR.instances.data_tt_content__39__pi_flexform__data__general__lDEF__settings.description__vDEF_.updateElement();
                 FormEngine.Validation.validate();
             });
       });
});

the CKEDITOR Object make the eventhandling to onChange with the requlare dots, but with spaceing dots in my variable broke the settings.

From:
CKEDITOR.instances.data_tt_content__39__pi_flexform__data__general__lDEF__settings.description__vDEF_.on('change'

Must change to:
CKEDITOR.instances['data_tt_content__39__pi_flexform__data__general__lDEF__settings.description__vDEF_'].on('change'

Thx :)