The empty lines might have to be with the new lines between </section> and the next <section> Try setting everything on one line.
Seems you're right. Although I can't really follow the way the content is parsed and rendered. Somebody who can explain it to me maybe?
Because another problem I figured out is to label single table-lines with tags like this.
{| border="1" |align = "center"|'''ID''' |align = "center"|'''Vorname''' |align = "center"|'''Nachname''' |- |1 |Stefan |Schmitt |- <section lan=de> |2 |Michael |Turner |- |3 |John |Foaley |- |4 |Max |Teofanis |- </section> |5 |Horst |Giggler |- |6 |Julius |van Horden |- |}
But what I get if I try this is the following...
|2 |Michael |Turner |- |3 |John |Foaley |- |4 |Max |Teofanis |- ID Vorname Nachname 1 Stefan Schmitt 5 Horst Giggler 6 Julius van Horden