Hardcore Story Mode scales on Player Level, but not for this Fight. Im starting the Story Mission with Level 27 Ranger wearing Brissa +10 Set and the Robos inside Two Hit me. They must have ~50k HP so i think, his Level is set on Level 70 or 75. If i start this Fight with my Level 75 Force,the Mobs inside have the same HP+Damage.

It is intentional. There are several Story Missions that have a fixed level on Hardcore because they are meant to be challenges, and this quest is one of them; another example is an Episode 4 Epilogue Quest where you can only play on Hardcore and the enemy is set to lv80.

Ah ok TY. Good to know.