kol. weapons testing in space would surely advance rocket technology, and if universalis is even a bit similar to irl, it's much easier to get funding for military purposes.
not that i think they shouldn't be banned or anything, kallisto doesn't pay too much attention to treaties
You can use rockets for other things than weapons so if you were interested in advancing rocket technology in itself, putting weapons on them aren't a very efficient way to do that. As for funding for military purposes being easier than for civillian technology, whether that reflects reality or not that problem should easily vanish within a planned economy where the state has total power over where resources are allocated.
Of course, there would be no point in making these treaties if they are ignored by countries, so that would leave us with the choice to give up the treaties, or impose sanctions, such as refusing to trade and cooperate, etc. with states that don't follow the treaties.