How this works is that you print a shitload of sprites on the users screen. CmdStart is called on every server frame, let's say 200 times per second. The sprite have a predefined set of frames to be shown, let's say 1.
https://wiki.alliedmods.net/Temp_Ent...:_TE_EXPLOSION
Reading that gives you really only one parameter to mess with, framerate. The highest possible value is 255, which means 25.5 FPS. So if that sprite is drawn and has one frame it will not disappear until ~.039 seconds later. CmdStart will be called with a delay of .005 seconds meaning about 8 times in the lifetime of that sprite, creating new sprites. These are the ones you see.
You can mess with the server FPS to be 25.5 to try to line it up, but I don't think you want that.
Another option is to not call it on every frame, just every 8th for example (if server has 200FPS). But this would cause the crosshair to drag behind instead.
You might be able to tweak it but it will never be perfect. You will either have flickering if you show too few sprites or duplicates if you show too many.
The rotation doesn't seem to be editable in this kind of message.
There might be another way to achieve what you want, I have no idea. I just thought I would explain a part of the problem.