Recondite means obscure and requiring specialized knowledge. It matches with complex sentences and limited appeal.

Vituperative means abusive or harshly critical. It fits with damaging comments about competitors.

Assiduous (diligent) efforts contrasted with abstruse (difficult to understand) subject matter.

Equivocal (unclear/contradictory) account with protestation (assertion of innocence) creates appropriate contrast.

Obstinate refusal paired with callous (indifferent) attitude logically explains disregard for grievances.

Unorthodox (unconventional) campaigns being more efficacious (effective) creates logical contrast.

Comprehensive analysis becoming irrelevant due to market changes shows impact of unforeseen events.

Unconventional yet striking design faces real-world implementation issues logically.

Inflammatory rhetoric exacerbates tensions rather than resolving them.

Tendentious (biased) portrayal is anachronistic (historically inaccurate) when driven by ideology.