The grammar is relatively simple. In general having syntactic constructs that are seen as complex by humans (on the grounds of unreadability or counterintuitive

The grammar is relatively simple. In general having syntactic constructs that are seen as complex by humans (on the grounds of unreadability or counterintuitiveness) says nothing about complexity of the formal language that describes such constructs (and in fact for most practical languages often ugly constructs are the effect of the grammar being simple, not the other way around, for somewhat extreme example of this try comparing say SQL and RPN).