I’m not sure why you have the impression you are bad at sprinting, your sprinting power seems to be better than your FTP would suggest. In fact, your best ability seems to be 15 second power, which is still a sprint in anyone’s book! Don’t sell yourself short.
Still, you may want to get better. What trainer are you using? IMHO quite a few of TR’s workouts include sprints (e. g. Pettit +1 and Mokelumne), but if you really want to go for it, you must switch from erg to resistance mode. Otherwise you are limited to 180-200 % or so that TR seems to prescribe max.
The only small accommodation you have to make is you have to be slightly less explosive than on the road. Otherwise the belt slips on my direct drive dumb trainer, and I reckon this will be a problem for wheel-on trainers, too. Nevertheless, It’s not a problem fore me to put out max sprint power, or something very, very close to it.
If you want to practice sprinting outside, I recommend you do this in addition to TR indoor sprint drills. Because the technique is different, especially if you go out of the saddle. However, make sure you find a suitable and safe piece of road, though.