Jagdpanther is worse version of the Elefant so why you want it in game?
Hetzer was weak, Jagdpanzer seems more viable
Jagdpanther was infact the best tank destroyer of the war. It combines the performance of the long 88mm/L71 with the mobility of a goddamn Panther. Frontal armor is still that of a Panther and couldn´t be penetrated by anything smaller than a ISU-152. In fact the Jagdpanther was a success and the Elefant was a flop. Imagine you have a Panther with teh range and gun of the Elefant - definitely better than that "mobile" bunker the Elefant is right now.
Hetzer was available in relatively huge numbers at the end of the war (for the German army that is). It was despite being small still able to fight medium tanks. In fact the frontal armor of the Hetzer was 60mm and so well sloped that even the 85mm gun couldn´t go through it beyond 300m.
From a gaming perspective both tanks could very well fit in the game in an actual tank destroyer doctrine (not the pseudo one that has the Elefant). It would be nice to actually be able to hunt soviet tanks rather than sitting around with the Elefant or running away from Su-85.