Don't forget that right now we have grenade size stuff that is dropped from very high up. sphere shaped grenades.
even with honest strike, we can expect to have trouble to pinpoint targets to the accuracy needed. Personally, I think we need to go big in size or in number.
I'll draft a couple proposals, names are placeholders.
Air dropped bomb
This substitutes the current bombs used by the firestorm. it is an upscaled blastgem slightly bigger than a blastshell, with significantly more explosive power due to not needing to add propulsion.
In addition to the size change, the other modification is the shape of the shell. No longer a simple sphere, now it uses the lessons learned from our aerodynamic shells to drop straighter toward the ground, improving accuracy.
Higher accuracy and bigger blast size should help greatly in making this an effective weapon.
or
Multiple area covering bomblet
Accuracy from the clouds is hard. The trick is not needing it. Instead of dropping a single grenade, the firestorm now drops an hail of many bomblets, a bit smaller than the current grenades. While the individual destructive power is lower, the spread of bomblets allows to cover a larger area. Aerodynamic knowledge is applied to the bomblet to reduce the spread size from "city" to "on the enemy side of the battlefield".
being able to carpet bomb an area should produce results even if we dont' have the required accuracy to pinpoint a single target. We just drop a lot around the entire thing and we will hit stuff.
@RAM having continuous thrust all the time, compared to just a big extra blast at the beginning, will surely increase speed. Plus, eliminating the impulsive propulsion of the current blastshell may improve accuracy on its own.