[freefriedrice]

After working int he world of CAD tools for decades, I cannot tell you the number of times I've seen a younger engineer try to write a CSV parser only to fall into a circular hacking deathspiral.

You can't just use regex/split to handle CSV, unless you have significant field cleaning BEFORE converting to csv.

In reality you need lexical analysis and grammatical rules to parse any string of symbols. This is often always overlooked by naive implementations.

I take issue with OP's claim that RFC4180 is not well-defined, but almost all of the cases the OP listed are literally in the spec.