If the Lvov Pocket option 'needs' to be nerfed by increasing CV or random placement, then perhaps extending AGS/Romanian ZOCs as "Active" on turn one, even if they can't move, would a nice way allowing the cutting of rail lines ( perfectly fine) while preventing massive escape or supply through (Noveletsky?) other unreachable rail lines. (unless they already are :)
That would make it more of a "What if Rumanians and 17. Army had finished Op. Marita a week early and where ready to strike sooner" type scenario, but why not? This is at least more credible than sneaking my Panzerdivisions and Regiments through the gaps for a full turn while the Soviets sit at the roadside and cheer...
As I said earlier, I would not want Lvov to be entirely impossible, nor the possibility of rounding Minsk in one turn. But I think it should not happen without a fight, and without the Soviet side having a chance to save some part of the units. Essentially I would like best if it were tuned so that if Lvov fails and Minsk progress is also "only" historical, the Soviet would have enough units left to fight and counterattack as we can read about it, and that on average he would be capable of delaying Axis advances while bleeding my units some ~30-40% so that they'd be truly ripe for a real, non-rule aided blizzard counteroffensive. In essence, that neither Leningrad nor Moscow are a given but both are possible, especially d if focused on. On the other hand, if Lvov despite fighting succeeded, then I'd have to be happy and allow the Soviet to retreat to regain some balance.