thanks. i thought it would end like that. makes sense. shapr3D has to calculate so many different objects. maybe its just an over kill and on some point after doing substract like 500 objects, its overheated 
the only way would be reverse engeneering by pathing it from the bottom. Because its the “Cupra” letters from the car brand Cupra. Seat and Cupra have houseown fonts they use, so no free available. And redrawing it i would lose details again, its an already redrawn (or 3D Scanned idk).
But: i just redone the whole thing again. But this time i setted the anchor for the pattern (circular) on a point that isnt crossing one of the letters. With this, i dont even get that parts i tried to substract away.
in the screenshot, i marked the origin letter. also the anchor point for patterns is visible. the part is now flat.
