It's annoying AF that smoke makes the SL unwittingly put fire support right on top of himself and his men. It's also annoying to have to be in LOS to call support.
Observer feels more like SL's pet, babysitter or personal bodyguard. It's not an active role at all. Also nothing distinguishes observer from other roles visually.
SO, the sugggestions:
Make SL call fire support using a map. It will fix the problem with smoke putting it in random spots. It will make the SL have to think an apply practical skills - reading a map. It will also allow for the SL to benefit from communicating with his team who can pass the intel with desirable coordinates to him. Team work makes the dream work.
Now, for the Observer. Add the radio as a visual item. Make it a selectable item. Make observer use it to pass SLs order only when it's selected. Possibly, after orders were given, show a prompt for the Observer to click. This would make the SL-Observer team benefit from cover of the rest of the team. It would also make Observer be a more involved, authentic and satisfying role to fulfill.
The downside is that even fewer people would go for those roles... The upside, on top of being awesome, cool, authentic and satisfying, is that it would take more skill, punishing those teams that ignore the roles and rewarding those who put in the effort. It would also make immersion even more awesome and make the SL/Observer a less gun-ho-rushy classes like they are now. And oh boy does the immersion of this game sell it to me. I think it would be great for Sandstorm to make it stand out from the flood of FPS games out there even more.