TYPO3: Override RTE CKEditor configuration preset for plugin flexform

In my TYPO3 sitepackage extension I have two different CKEditor configuration presets: a default one and a minimal one with less options.

In my page.tsconfig I define the default configuration and set the minimal configuration for certain fields, which works well for regular tt_content fields as well as for RTE text fields of other extensions. I cannot make it work though for text fields in a plugin flexform.

According to documentation it should work by using RTE.config.[tableName].[flexForm.field.name].preset even with an example for tt_content as tableName – but it doesn’t. Is there any mistake I overlook?

page.tsconfig

RTE {
    default.preset = MyDefaultCKConfig
    config {
        tx_another_extension_model_xyz {
            ## this works
            field_name.preset = MyMinimalCKConfig
            another_field_name.preset = MyMinimalCKConfig
        }
        ## the following does not work
        tt_content.settings.flexform.textAdd.preset = MyMinimalCKConfig
    }
}

Plugin Flexform definition (excerpt)

<settings.flexform.textAdd>
    <TCEforms>
        <exclude>1</exclude>
        <label>LLL:EXT:tx_another_extension/Resources/Private/Language/locallang_be.xlf:flexform.pluginName.textAdd</label>
        <config>
            <type>text</type>
            <cols>40</cols>
            <rows>5</rows>
            <enableRichtext>true</enableRichtext>
        </config>
    </TCEforms>
</settings.flexform.textAdd>

The comment by Christian Fries revealed the solution. I post it here so that others can find it more easily.

The dots in the actual settings field settings.flexform.textAdd – and only these – need to be escaped:

RTE {
    default.preset = MyDefaultCKConfig
    config {
        tt_content.settings\.flexform\.textAdd.preset = MyMinimalCKConfig
    }
}