[TYPO3-templavoila] Problem with migration of charset to utf-8

[Kay Strobach]

Hello List,

i migrated the Typo3 Installation on 
http://www.sn.schule.de/cms/sba-offener-unterricht/faecherverbindender-unterricht/klasse-8/reis-ein-kleines-korn-ernaehrt-die-welt/ 


to UTF8 with convert2utf8
http://typo3.org/extensions/repository/view/convert2utf8/1.0.6/

this works nearly perfectly for all the elements in tt_content. but not 
for the fce's you see on the page linked above.
BUT THE FIELDS IN THE BACKEND ARE EMPTY!!!
As i understand the tablestructure of typo3

SELECT `tx_templavoila_flex` FROM tt_content WHERE `tx_templavoila_flex` 
  LIKE '%xml%'

greps all fce elements, f.e.:
----------------------------------------------------------------------------------------
<?xml version="1.0" encoding="iso-8859-1" standalone="yes" ?>
<T3FlexForms>
     <data>
         <sheet index="sDEF">
             <language index="lDEF">
                 <field index="field_orga">
                     <value index="vDEF">Arbeit klassenübergreifend in 
Kleingruppen zu maximal 15 Schülern</value>
                 </field>

[... here is more content ...]

             </language>
         </sheet>
     </data>
</T3FlexForms>
----------------------------------------------------------------------------------------

I use Typo3 4.1.6, PHP 5.2.x, MySQL 5.0.27 => do you have any hint how 
to get the fields filled up with content again???

Regards Kay