Regex CSV : Match quotes that are not delimiters
Solution 1:
Your regex with negative lookarounds containing positive character classes can be transformed into a pattern with positive lookarounds containing negated character classes:
(?<=[^;\n\r\t])"(?=[^;\n\r\t])
See the regex demo. The replacement will be an empty string.
Now, the match will only occur if there is a " that is immediately preceded and followed with any char but ;, CR, LF or TAB.