[microtonal]

Not exactly an expert system, but during my PhD I contributed to a natural language parsing/generation system for Dutch written mostly in Prolog with some C++ for performance reasons. The only statistical component was a maxent ranker for disambiguation and fluency ranking.

No statistical dependency parser came near it accuracy-wise until BERT/RoBERTa + biaffine parsing.

[arnsholt]

Oh yeah, the good hand crafted grammars are really good. For my PhD I worked in a group that was deep in the DelphIN/ERG collaboration, and they did some amazing things with that.