For Masado Oseiji, the point of making it a projectile is that your opponent can see it coming and react. Maybe instead it has some other up-front warning, like a certain feeling that occurs two seconds before the actual effect. Still questionable though, as most people wouldn't know what to do with it.

As for Gamo Tan, make it any lower and it won't be lighting anything. I think it might work the way it is, but it needs a visibility factor. Because hot air just looks like air, it's too easy to put it in front of someone and have them walk into it for easy damage. Alternatively, perhaps you could replace it with some kind of small electric spark? Sparks can light stuff on fire, are more visible than hot air and sometimes less harmful in direct contact.