compatibility / harmonization

disputable, controversial

verbose, long-winded / nitpicky, faultfinding, quibbling

five year-old horse

Chelyabinsk (an oblast of Russia, near the Ural Mountains) / Chelyabinsk (a city, the administrative center of Chelyabinsk Oblast, Russia)

Medina (the capital city of the Medina region, Saudi Arabia, holy to Islam)

Nizhny Novgorod (an oblast of Russia) / Nizhny Novgorod (a city, the administrative center of Nizhny Novgorod Oblast, Russia)

mutual, reciprocal

mutually, reciprocally

Kazan (the capital and largest city of the Republic of Tatarstan, Russia)