Yes, The Happy Cadavres is definitely a goth band because most of their albums belong to the Gothic Rock genre, which is a core subgenre of goth music. Albums like First Kiss and Autumn are examples of their goth sound.
The Happy Cadavres is located in Germany, Saxony-Anhalt, Magdeburg, active in 1989 — 1993. You can find more information about The Happy Cadavres on their GothDB band page.