First we should distinguish between between grammatical and derivative affixes. The prefixes you present here are derivative. Svartiska has a few derivative affixes. But are you really asking whether there only ought to be derivative suffixes or prefixes too?
In zhâburi A (my first version of the language) I used both pre- and suffixes but for Zhâburi B my idea was to only use suffixes. But then I made the analysis of the words uruk, olog and oghor as being constructed by a mono syllabic stem with a prefixed duplication of the stem vowel, so: ruk > uruk; log > olog >; ghor > oghor.
Read more here: https://zhaaburi.wordpress.com/2017/11/ … log-oghor/
These are listed by Adragoor for Svartiska
-at Creates verbs from nouns, e.g. ghâsh “fire” > ghâshat “to burn”, “to fire”
-urz Creates adjectives from nouns, e.g. ghâsh “fire” > ghâshurz “hot”
-um Creates nouns of adjectives, e.g. burz “dark” > burzum “darkness”
-atâr Creates agents or job titles, e.g. ush “combat” > ushatâr “warrior”
Then there is the prefix ga- which I learned from the one who introduces me to Svartiska. And then there are a some that I analysed that seems to actually function as derivative prefixes but are not listed as such:
mi- creates nouns or alternative nouns gûl "wraith" > migûl "mist"
ka- Creates alternative nouns dar “house” > kadar “tent”