Thank you, charghwI' and Voragh for your replies! I think it was the *romuluS HIq* and how the name of languages are formed in Klingon that made me think origin is expressed in noun-noun constructions with the name of the planet/country/region, and not with the name of the inhabitans. Voragh:
The basic idea is that {romuluSngan} refers to people and things related to them while {romuluS} refers to things characteristic of the planet, like {romuluS muD} the Romulan atmosphere, {romuluS Hovtay'} the Romulan star system, etc. So a {romuluSngan Sambogh 'ej HoHbogh nejwI'} was invented and/or originally used by or against Romulans (people) and the {loSmaH romuluSngan SuvwI'pu'} Kang killed were Romulan people too.
Sorry if I ask again: I understand what you mean with *romuluS muD* and *romuluS Hovtay'* as *things characteristic of the planet*, even *romuluS Ha'DIbaH*, but then we have these examples: Voragh:
romuluS yo' wIjeyta' We've defeated the Romulan fleet. KGT
boq lucherDI' tlhIngan wo' romuluS Hov wo' je So'wI' cham Suqpu' tlhIngan wo'. Cloaking technology was gained through an alliance with the Romulan Star Empire... S33 Federation's precious Earth, are all up for grabs. MKE
Dujon romuluS Duj Captured by Romulan ship. MKE
Especially the last one makes no much sense to me if compared to *romuluSngan Sambogh 'ej HoHbogh nejwI'*. A *Duj* or a *nejwI'* are both things invented/used by the (Romulan) people and not directly things charasteristic of their planet (?). charghwI':
It’s common to arbitrarily pick the name of a place or of the inhabitants in a Noun-Noun construction
Maybe it's just as charghwI' says something which is chosen arbitrarily? Thank you for your patience!