Actually, in the late 80's, two titles of Tintin were published in Latin:
The first one only contains the characters Tintin, Milu, and the two detectives. The vignettes available here confirm the names in the above list, based on standard declensions (_Tintinus, Milulus, Clodius and Claudius).
The second book also contains Rastapopoulos, but I haven't found a page online with his name. The image here has, funnily enough, his first appearance in the comic but doesn't mention his name. However, being a Greek name suggests to me the Latin was probably equivalent. Greek experts in this forum may know better than me.
On another note, this post from 2009 mentions a Finnish medical doctor called Ylermi Luttinen was translating Tintin's books into Latin. Goolging that name it seems he is part of the recurrent event called "Athenis Finlandiae", which promotes Latin in Finland, meaning he might be proficient in Latin. I haven't been able to find a contact or website (and the one linked on the post doesn't work anymore). Maybe Joonas can help on this?