Well, I did not recognise here, that you are using dexterity.
You need the dexteritytextindexer
behavior:
https://github.com/collective/collective.dexteritytextindexer
Enable this on your container type.
<property name="behaviors">
<element value="collective.dexteritytextindexer.behavior.IDexterityTextIndexer" />
</property>
With the dexteritytextindexer you have a different approach to index the data on your container. Check the dexteritytextindexer.IDynamicTextIndexExtender
.