Be caught between two stools - Tradução em português

Estou tentando traduzir esta expressão ou encontrar um equivalente no português. É um pouco difícil porque observando os contextos parece complicado encontrar similaridade. O que vocês acham?

Vejam as sentenças e exemplos:

This book cannot be an academic one nor can it be a popular commercial one; it falls between two stools.

It is difficult to organize an event that appeals to both young and old; you could end up being caught between two stools.

This car neither has good power nor gives good mileage; it falls between two stools.
Do not try to be both a teacher and a friend to your students; you would be caught between two stools.

This tutorial is too complicated for a beginner and too simple for an advanced student. It falls between two stools.

Don’t try to club a relaxing vacation with an adventurous one; it would fall between two stools.

Como vocês traduziriam?