Complex sentence: However, the Slovak part did not observanced their legally binding undertaking, wich was that Slovakia has pledged to introduce the same standards enshrined in Hungarian wine laws since 1990, but it has not yet been decided who will monitor or enforce those laws.
Split into simpler sentences: However, the Slovak part did not observe their legally binding undertaking, which was to introduce the same standards enshrined in Hungarian wine laws since 1990. It has not yet been decided who will monitor or enforce those laws.