It's not a "spoiler" that the character is duplicitous, though. Within minutes of meeting him Frieren tells the rest of the cast exactly what his deal is. You aren't gaining speed on the story by understanding his name. It's like saying the character in 101 Dalmatians obviously being named Cruel Devil is spoiling the movie for you.

Also, Lugner appears to be a real and well known actual last name, see https://en.wikipedia.org/wiki/Richard_Lugner

Nominative determinism is a really common concept in fiction, and in anime and manga especially.