Pretty sure that if every variant of every sub type that is already in the mod was included, including the Golf, there would be hundreds of subs in the mod.
This is especially true of the Soviet cold war era subs. The Soviets were
extremely experimental with their sub designs during this period, with many types having a number of one-offs and other prototype experimental designs going to sea.
Can't expect all of them to be modeled. The line of context and relevance has to be drawn at some point.